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MODERN 


TURBINE    PRACTICE 


AND 


WATER-POWER  PLANTS 


BY 


JOHN    WOLF    THUKSO 

Civil  and  Hydraulic  Engineer 


SECOND     EDITION,    REVISED 


NEW  YORK 

D.    VAN    NOSTRAND    COMPANY 

23  MURRAY  AND  27  WARREN  STREETS 
1907 


Engineering 
Library 

Copyright,  1905,  1907 

BY 

D.  VAN  NOSTRAND   COMPANY 


ROBERT  DRUMMOND,  PKINTKR,   NEW  YORK 


PREFACE. 


Two  years  ago  the  writer  published  in  Engineering  News  some 
articles  on  modern  turbine  practice,  and  the  encouragement  given 
by  progressive  engineers  led  him  to  rewrite  these  articles,  to  make 
large  additions,  and  to  include  new  subject-matter,  which  together 
form  the  contents  of  this  volume. 

The  object  of  this  book  is  to  give  such  information  in  regard  to 
modern  turbines  and  their  proper  installation  as  is  necessary  to 
the  hydraulic  engineer  in  designing  a  water-power  plant,  and  no 
attempt  has  been  made  to  treat  on  the  design  of  turbines,  as  to  do 
this  satisfactorily  would  require  in  itself  a  very  large  volume. 

The  writer  has  designed  turbines  both  in  America  and  in  Europe, 
and  has  been  connected  in  engineering  capacities  with  water- 
power  developments  aggregating  nearly  200,000  H.P.,  having 
been  in  charge  of  the  hydraulic  work  during  the  planning  and 
construction  of  some  of  the  most  important  developments  in 
Canada.  The  writer  therefore  had  an  excellent  opportunity  to 
study  the  subject  from  the  point  of  view  of  both  the  turbine  builder 
and  the  turbine  user  and  thus  became  convinced  of  the  necessity 
of  thorough  changes  and  improvements  in  the  American  turbine 
practice. 

In  the  first  part  of  this  book  the  writer  has  shown  the  deficien- 
cies of  the  present  American  turbine  practice  and  pointed  out  the 
direction  in  which  improvement  is  to  be  sought.  It  should  not 
be  inferred  that  what  is  said  here  regarding  turbine  design  and 
construction  is  intended  to  depreciate  the  American  and  praise  the 
European  practice.  Considered  as  a  hydraulic  motor,  each  type 
has  a  field  of  its  own,  where  it  should  be  used  in  preference  to  the 


794025 


Iv  PREFACE. 

•other.  The  present  European  practice  has  only  been  evolved 
during  the  last  ten  years  and  is  yet  in  a  transition  state,  so  that 
•changes  and  improvements  are  continually  being  made. 

The  American  standard  type  of  turbines  has  not  been  shown 
in  the  illustrations,  as  every  hydraulic-power  engineer  is  sufficiently 
familiar  with  it  through  the  engineering  press  and  the  turbine 
catalogs. 

On  account  of  the  growing  importance  of  the  steam-turbine 
and  its  close  relation  to  the  hydraulic  turbine,  the  writer  has  in- 
cluded a  chapter  on  this  subject. 

In  the  second  part  of  this  book  will  be  found  information  and 
data  about  matters  connected  with  turbine  plants.  These  were 
either  taken  from  the  writer's  personal  experience  or  collected 
from  recent  volumes  of  the  American  and  European  engineering 
press. 

Of  course  there  are  instances  where  the  refinement  in  turbine 
design  and  construction  here  recommended  does  not  pay,  being 
either  unnecessary  or  impracticable.  For  example,  the  backwoods 
sawmill,  moving  with  the  pioneer  settler  into  newly  opened  ter- 
ritory, will  do  best  with  the  roughest  kind  of  a  turbine  plant. 

The  opinion  of  engineers  in  regard  to  many  statements  made 
in  this  book  may  vary  from  that  of  the  writer,  and  no  hard  and 
fast  rules  can  be  laid  down  for  water-power  developments,  as 
every  case  demands  a  careful  and  intelligent  judgment,  requiring 
greater  experience  on  the  part  of  the  planning  engineer  than  most 
other  classes  of  construction  work. 

At  the  end  of  this  book  will  be  found  Mr.  Allan  V.  Garratt's 
paper  on  speed  regulation  of  turbines,  and  the  writer  begs  to  thank 
here  Mr.  Garratt  and  the  American  Institute  of  Electrical  Engi- 
neers for  their  kind  permission  to  reprint  this  paper. 

JOHN  WOLF  THURSO. 
May,  1905. 


ILLUSTRATIONS. 

The  writer  is  indebted : 

For  the  plates  for: 

Fig.  11,  to  The  Westinghouse  Machine  Co.,  Pittsburg,  Pa. 
Figs.  12  and  13,  to  the  De  Laval  Steam  Turbine  Co.,  Trenton,  N.  J. 
Fig.  14,  to  The  General  Electric  Co.,  Schenectady,  N.  Y. 
Figs.  72  to  74,  to  The  Engineering  News  Publishing  Co.,  New  York,  N.  Y. 

For  the  drawings  for: 

Fig.  24,  to  the  Montreal  Light,  Heat,  and  Power  Co.,  Montreal,  Que. 
Figs.  35,  45,  and  46,  to  Messrs.  Stilwell-Bierce  &  Smith-Vaile  Co.,  Dayton,  O. 
Fig.  59,  to  The  Lombard  Governor  Co.,  Boston,  Mass. 
Fig.  60,  to  The  Replogle  Governor  Works,  Akron,  O. 

The  following  illustrations  were  reproduced  from : 
G.  Meissner,  "Die  Hydraulik  und  die  hydraulischen  Motoren,"  Vol.  2.  Jenaf 

1896-97.     Figs.  1  and  2. 

The  Canadian  Engineer,  Toronto,  Ont.     Figs.  15  to  18,  75  and  80. 
Zeitschrift  des  Vereins  deutscher  Ingenieure,  Berlin,  Germany.     Figs.  5  to  7, 

19  to  23,  26  to  34,  36  to  44,  47  to  56,  66  to  69,  and  76  to  79. 
Schweizerische  Bauzeitung,  Zurich,  Switzerland.     Figs.  3  and  4,  8  and  9, 
25,  and  61  to  65. 


FOOT-NOTES. 

The  names  of  some  of  the  books  and  periodicals  frequently  referred  to 

in  the  foot-notes,  being  inconveniently  long,  have  been  abbreviated  as  given 

below;  and  as  in  all  cases  the  number  of  the  page  or  illustration  is  mentioned, 

the  edition  of  the  books  used  is  also  given. 

Frizell.  Water-power. — Water-power:  an  Outline  of  the  Development  and 
Application  of  the  Energy  of  Flowing  Water.  By  Joseph  P.  Frizell. 
2d  edition.  New  York,  1901. 

Meissner.  Hydraulische  Motoren. — Die  Hydraulik  und  die  hydraulischen 
Motoren.  By  G.  Meissner.  2d  edition.  Jena,  1895-99. 

Mueller.  Francis-Turbinen. — Die  Francis-Turbinen  und  die  Entwicklung  des 
modernen  Turbinenbaues.  By  Wilhelm  Mueller.  1st  edition.  Han- 
nover, 1901. 

Schweiz.  Bauz. — Schweizerische  Bauzeitung.     Zurich. 

Stodola.  Steam  Turbines. — Steam  Turbines.  By  Dr.  A.  Stodola.  Trans- 
lated from  the  German  by  Dr.  Louis  C.  Loewenstein.  New  York,  1905. 

Taschenb.  Huette. — Des  Ingenieurs  Taschenbuch.  Herausgegeben  vom 
Verein  Huette.  17th  edition.  Berlin,  1899. 

Wood.  Turbines. — Turbines,  Theoretical  and  Practical.  By  De  Volson. 
Wood.  2d  edition.  New  York,  1896. 

Zeitsch.  d.  V.  deutsch.  Ing. — Zeitschrift  des  Vereins  deutscher  Ingenieure. 
Berlin. 


CONTENTS. 


PAGE 

TERMS  AND  SYMBOLS  USED  IN  HYDRAULIC  POWER  ENGINEERING xiii 


PART  I. 

MODERN  TURBINE  PRACTICE. 
v 

CHAPTER  I. 

TURBINE  PRACTICE  IN  EUROPE 1 

Turbine  Development  in  Europe 1 

Present  Turbine  Practice  in  Europe 5 

Turbine  Pumps 13 

CHAPTER  II. 

TURBINE  PRACTICE  IN  AMERICA 17 

Turbine  Development  in  America 17 

Present  Turbine  Practice  in  America.     The  Turbine  as  a  Hydraulic 

Motor 19 

Present  Turbine  Practice  in  America.     The  Turbine  as  a  Machine.  .  27 
Causes  of  Lack  of  Progress  Among  American  Turbine  Builders ...     30 

CHAPTER  III. 

CLASSIFICATION  OP  TURBINES 37 

The  Reaction  Turbine 38 

The  Action  Turbine 49 

The  Limit  Turbine 54 

CHAPTER  IV. 
STEAM  TURBINES „ 57 

vii 


Viii  CONTENTS. 

CHAPTER  V. 

PAGE 

MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION 73 

Turbine  Construction  in  General 73 

Turbines  for  Low  Heads 83 

Turbines  for  Medium  Heads 95 

Turbines  fgr  High  Heads 108 

Manufacture  of  Turbines. 119 

CHAPTER  VI. 

ACCESSORIES  TO  TURBINES 124 

The  Draft-tube 124 

Stop-valves  for  Turbines 132 

Throttling-gates  for  Speed  Regulation 134 

Gages 137 

CHAPTER  VII. 
GOVERNORS  AND  SPEED  REGULATION .  139 


PART  II. 
WATER  POWER  PLANTS. 

CHAPTER  VIII. 

WATER-CONDUCTORS 161 

Headrace  and  Tailrace 161 

Water-racks 163 

Head-gates 165 

Penstocks 169 

CHAPTER  IX. 

THE  DEVELOPMENT 180 

Developing  a  Water-power 180 

Surface,  Anchor  and  Frazil  Ice 187 

Measurement  of  Water  for  Selling  Water-power 193 

Cost  of  Water-power 196 

BRITISH  AND  METRIC  MEASURES  AND  VALUES 199 

APPENDIX. 

ELEMENTS  OF  DESIGN  FAVORABLE  TO  SPEED  REGULATION  IN  PLANTS 
DRIVEN  BY  WATER-POWER.     BY  ALLAN  V.   GARRATT 203 

INDEX.  239 


LIST   OF  ILLUSTRATIONS. 


*'  }  50-100-H.P.  Turbine  at  the  Water-works  of  Geneva,  Switzerland.  .      2 

3. 1  Zodel  Register  Gate.     Gate  Shown  in  Open,  Half-closed,  and  Closed 

4.  J        Position 7 

5.  5500-H.P.  Turbine  for  Power  House  No.  2  of    the  Niagara  Falls 

Power  Co.,  Niagara  Falls,  N.  Y 10 

**'  \  Quadruple  Turbine  Pump 15 

8.  \  Vane  of  Runner  and  Section  through  Runner  and  Guide,  of  American 

9.  /        Type  of  Turbine 23 

10.  Diagram  of  Guide  and  Runner  Bucket,  Showing  Angles  and  Veloci- 

ties   42 

11.  Longitudinal  Section  of  Westinghouse-Parsons  Steam  Turbine 63 

12.  Runner  and  Nozzles  of  De  Laval  Steam  Turbine 66 

13.  Horizontal  Section  of  De  Laval  Steam  Turbine,  with  Direct  Con- 

nected Dynamo 68 

14.  Diagram    of    Curtis    Steam    Turbine,    Showing    Nozzles,    Runner 

Buckets,  and  Deflecting  Vanes  for  First  and  Second  Stage 70 

15. 1  Proposed  Vertical  Arrangement  of  Turbines  for  the  Power  House  of 
16.  J        the  Shawinigan  Water  and  Power  Co.,  Shawinigan  Falls.  Que.. .     76 

1  Horizontal  Arrangement  of  Turbines  for  the  Power  House  of  the 
'  I  Shawinigan  Water  and  Power  Co.,  Shawinigan  Falls,  Que.,  as 
'  J  Actually  Installed 77 

19.  Cross-section  of  Power  House  of  the  Elektrizitaetswerk  Beznau, 

Beznau,  Switzerland 85 

20.  Cross-section  of  Power  House  of  the  City  of  Lyon,  near  Lyon, 

France 87 

21.  Cross-section  of  Power  House  of  the  City  of  Geneva,  at  Chevres, 

Switzerland 88 

22.  ^  3000-H.P.  Turbine  for  the  Electric  Works  on  the  River  Glommen, 

23.  J        Norway 90 

24.  Cross-section   of    Power    House    of  the    Montreal    Light,    Heat, 

and  Power  Co.,  at  Chambley,  Que 92 

ix 


X  LIST  OF  ILLUSTRATIONS. 

PAGE 

"25.     2500-H.P.  Turbine  for  the  Isawerk,  near  Munich,  Germany 94 

26  } 

27  1 104-H.P.  Turbine 98 

2Q  }  200-H.P.    Turbine 99 

e1 '  \  3000-H.P.  Turbine  for  the  Cataract  Power  Co.,  Hamilton,  Ont..  .    .   100 
01.  J 

|g- 1  1000-H.P.  Turbine  for  the  Bosnische  Elektrizitaets-Aktien-Gesell- 
34'  J        schaft,  Jajce,   Bosnia 101,  102 

35.  650-H.P.  Turbine  for  Messrs.  J.  &  J.  Rogers,  Ausable  Forks,  N.  Y. .   103 

36.  \  2160-H.P.  Turbine   for  the  Paderno  Power  House  of  the  Edison 

37.  /       Electric  Co.,  Milan,  Italy 105 

jjj*'  }  1200-H.P.  Turbine  for  the  Carbide  Works  at  Notodden,  Norway.  .    106 
•39.  J 

1?'  1 160-H.P.  Turbine .107 

41.  J 

^  j  600-H.P.  Turbine  of  the  Elektrizitaetswerk  Schwyz,  Switzerland. .  .    110 

45.  \  1000-H.P.  Turbine  for  the  Ouiatchouan  Pulp  Co.,   Ouiatchouan, 

46.  J        Que Ill 

47.  1  1000-H.P.  Turbine  for  the  Walliserlndustrie-Gesellschaft,  Vernayaz, 

48.  J        Switzerland 112 

49  1 

'  >  Runner  of  a  Spoon-turbine 113 

50.  J 

51.1 

52.  [  360-H.P.  Impulse  Turbine 116 

53.  J 


M  500-H.P.  Impulse 
!'  J        St  Gallen,  Swil 


Ise  Turbine  for  the  Elektrizitaetswerk  Kubel,  near 

^u „,  Switzerland 118 

56.  J 

57. }  6000-H.P.  Turbine  for  the  Shawinigan  Water  and  Power  Co.,Sha- 

58.  /        winigan  Falls,  Que. 135 

,59.     Lombard  Pressure-relief  Valve 142 

•60.     Centrifugal  Governor  and  Return  of  Replogle  Governor 149 

>  Water-filter  for  Hydraulic  Governors 152 

63.     Hydraulic  Governor  for  Impulse  Turbines 154 

'64  "\ 

.'  \  Two  Forms  of  Temporary  By-pass 156 

'65.  J 

•66. 1 

67.  [  Hydraulic  Governor 158 

<68.  J 

•69.     Hydraulic  Governor 159 


LIST  OF  ILLUSTRATIONS. 


™'  |  Sectional  Water-rack 164 

nil 

73 

74'  f  Steel  Head-gate  with  Balance-port 166 

75  J 

1?'  |  Steel  Head-gate  with  Friction-rollers 168 

78. 


f  Pivoted  Steel  Head-gate 168 

79.  J 

80.  Steel  Pier  for  Penstock  of  9  Feet  Diameter 176 


QTIL  ENGINEERING 

D.  ol  C. 
ASSOCIATION  1.1 


NOMENCLATURE     AND    SYMBOLS     FOR 
POWER  ENGINEERING. 


HYDRAULIC- 


In  hydraulic-power  engineering  there  exist  so  far  no  gener- 
ally accepted  terms,  and  not  only  are  several  different  names 
given  to  most  things,  but  what  is  worse,  the  same  terms  are  often 
used  with  different  meanings. 

To  start  a  movement  towards  uniformity,  the  writer  would 
suggest  here,  for  universal  acceptance,  the  terms  and  meanings 
given  below;  and  these  terms  have  been  used  through  this  book, 
so  that  the  reader,  by  referring  to  this  nomenclature,  may  at  once 
know  exactly  what  is  meant. 

The  terms  here  suggested  are  already  used  to  a  greater  or 
less  extent;  they  are  not  only  simple  and  easily  remembered,  but 
most  of  them  directly  express  their  own  meaning. 

The  characteristics  and  properties  of  the  different  classes  of 
turbines  will  be  found  under  "Classification  of  Turbines." 

Uniform  symbols  have  also  been  employed  in  all  formulas 
.appearing  in  this  book,  and  the  following  system  has  been  used: 
All  heads  are  expressed  by  H,  parts  of  heads  by  h;  all  speeds 
of  water  by  c  (celeritas  or  celerity);  all  speeds  of  runners  by  v 
(velocitas  or  velocity)  and  all  efficiencies  by  y  (eta).  The  single 
letters  denote  in  all  cases  the  most  important  or  determining 
quantity  or  value,  while  all  other  quantities  or  values  are  denoted 
by  the  single  letter  as  a  base  and  an  index-letter,  the  latter  being 
the  inital  letter  of  a  word  which  as  nearly  as  possible  expresses 
the  particular  meaning  of  the  base  letter.  In  cases  where  not 
readily  understood,  the  word  for  which  the  index-letter  stands 
is  given  in  brackets. 

While  figures  or  dashes  are  more  generally  used  for  indices, 
the  writer  has  adopted  letters  for  this  purpose,  as  being  more 
easily  remembered. 


Xlll 


xiv 


NOMENCLATURE  AND  SYMBOLS. 


Action  turbine. — For  free-deviation  turbine,  such  as  the  Girard, 
etc.,  say  "action"  turbine. 

Axial  turbine.— For  "parallel-flow"  turbine  say  "axial-flow"  tur- 
bine, or  axial  turbine. 


Diagram  of  Guide-  and  Runner-bucket,  showing  angles  and  velocities. 

Bucket  angles. — All  angles  are  measured  from  the  tangent  at 
the  point  where  the  direction  in  question  intersects  the  cir- 
cumference. (See  figure.) 

a  =  terminal  angle  of  guide-bucket. 

/?= initial  angle  of  runner-bucket. 

7-= terminal  angle  of  runner-bucket. 

d= actual  angle  of  the  jet  of  water  at  exit  from  runner-bucket. 

Bucket  circle.  —  The  imaginary  circle  running  approximately 
through  the  centre  of  the  radial  dimension  of  the  buckets  of 
impulse  turbines  and  to  which  the  centre  line  of  the  jet  of 
water  is  a  tangent  should  be  called  "bucket  circle."  This 
circle  is  somewhat  similar,  in  its  importance  and  use,  to  the 
pitch  line  of  a  gear. 

Clearance. — The  clear  space  between  the  guide-ring  and  the  runner 
should  be  called  the  "clearance." 


NOMENCLATURE  AND  SYMBOLS.  XV 

Dip  of  draft-tube. — For  the  vertical  distance  to  which  a  draft- 
tube  reaches  below  the  surface  of  the  tailwater,  say  dip  of 
draft-tube. 

Draft-tee.— For  " draft-chest "  or  "camelback"  say  "draft-tee."1 
Efficiencies. — As  there  are  four  different  efficiencies  to  be  con- 
sidered in  connection  with  water-power  developments,  speci- 
fications and  contracts  should  always  state  which  efficiency 
is  meant;  also,  where  the  tests  are  to  be  made. 
fjh  =  hydraulic  efficiency.    This  is  the  ratio  of  the  power  actually 
developed  by  the  water  in  flowing  through  the  guides, 
runner,  and   draft-tube,  if  a  draft-tube  is  employed,  to- 
the   theoretical   power  due   to   the   effective   head.     The 
hydraulic  losses  are  the  friction  and  shocks  of  the  water 
in  guides,  runner,  and  draft-tube,  and  the  velocity  head, 
corresponding  to  the  absolute  velocity  of  the  water  at 
exit  from  runner-buckets,  or  to  the  velocity  of  the  water 
at  exit  from  the  draft-tube,  if  such  is  used.     Reports  ori 
efficiency  tests    should  always  state  if  a  draft-tube  was 
employed. 

r)m= mechanical  efficiency.  This  is  the  ratio  of  the  power  delivered 
at  the  end  of  the  turbine-shaft  to  the  power  actually 
developed  by  the  water  in  flowing  through  the  guides  r 
runner,  and  draft-tube,  if  a  draft-tube  is  used.  The  mechan- 
ical losses  are  the  loss  of  water  through  the  clearance,  the 
friction  of  the  runner  in  the  air  or  in  the  water,  according 
to  the  location  of  the  turbine,  and  the  friction  of  the  shaft 
in  its  journal-  and  step-bearings.  If  the  turbine  is  enclosed 
in  a  case,  the  friction  of  the  shaft  in  the  stuffing-boxes 
and  the  friction  of  the  water  in  the  case  itself  are  addi- 
tional losses. 

9  =  turbine  efficiency.  This  is  the  efficiency  of  the  turbine  as 
a  whole,  or  the  ratio  of  the  power  delivered  at  the  end 
of  the  turbine-shaft  to  the  theoretical  power  due  to  the 
effective  head.  The  turbine  efficiency  is  equal  to  the 
product  of  the  hydraulic  and  mechanical  efficiencies,  and 
takes  into  consideration  both  the  hydraulic  and  the  mechan- 
ical losses. 
fy  =  total  efficiency,  or  efficiency  of  the  entire  plant.  This  is- 


xvi  NOMENCLATURE  AND  SYMBOLS. 

the  ratio  of  the  power  delivered  at  the  end  of  the  turbine- 
shaft  to  the  theoretical  power  due  to  total  head  utilized 
in  the  development.  Besides  the  hydraulic  and  mechan- 
ical losses,  all  losses  in  the  headrace,  penstock,  tailrace, 
etc.,  are  here  taken  into  consideration. 

External-feed  turbine. — A  turbine  having  the  guide-ring  outside 
the  runner  and  discharging  inward  should  be  called  "  external- 
feed  turbine." 
Pull  turbine. — A  turbine  having  guide-buckets  around  its  whole 

circumference  is  a  "full  turbine." 
Gate. — The  term  gate  or  gates  should  always  mean  the  speed 

regulating  gate  or  gates  of  a  turbine. 

Gate  opening  and  discharge. — The  area  left  open  or  clear  by 
the  regulating  gate  or  gates  for  the  passage  of  the  water  should 
be  called  gate-opening.  At  present  the  term  gate-opening  or 
gate  is  nearly  always  used  to  mean  the  amount  of  water  flow- 
ing through  the  gate-opening,  but  this  amount  should  be 
designated  by  discharge;  for  example,  instead  of  saying: 
"This  turbine  with  five-eighths  gate-opening  gave  an  effi- 
ciency," etc.,  should  be  said:  "This  turbine  with  five-eighths 
discharge  gave  an  efficiency,"  etc.,  whenever  the  discharge 
is  meant. 

Heads  of  water,  in  feet. 
Ht  =  total  head  utilized  in  a  development. 

H= effective  head,  that  is,  the  head  available  at  the  turbine, 
equal  to  the  total  head  less  the  losses  in  headrace,  pen- 
stock, tailrace,  etc. 

h 4= draft-head,  that  is,  the  part  of  the  head  which  is  utilized  by 
means  of  a  draft-tube.  The  height  of  the  draft-head 
acting  on  a  radial-  or  parallel-flow  turbine  on  horizontal 
shaft  is  the  vertical  distance  from  centre  of  shaft  to  the 
tailwater  level,  while  the  draft-head  of  a  radial  turbine 
on  vertical  shaft  is  the  vertical  distance  from  the  level  of 
the  centre  of  the  guide-bucket  discharge-openings  to  the 
level  of  the  tailwater.  The  draft-head  of  an  impulse  tur- 
bine or  an  action  turbine  with  free  deviation  is,  of  course, 
the  vertical  distance  from  the  water  level  in  the  turbine- 
case  or  draft-tube  to  the  level  of  the  tailwater. 


NOMENCLATURE  AND  SYMBOLS.  XVli 

hp= pressure-head,  that  is,  the  part  of  the  head  which  is  above 
the  turbine  and  terminates  at  the  point  where  the  draft- 
head  commences,  as  explained  under  Draft-head. 
h= velocity-head,  corresponding  to  the  velocity  of  the  water 
at  exit  from  guide-buckets  of  reaction  turbines.  For 
action  turbines  this  velocity-head  is  H. 

h  r  =  head  remaining  as  pressure  of  the  water  at  exit  from  guide- 
buckets  of  reaction  turbines.     (H=h  +  hr.) 
ha= velocity-head,  corresponding  to  the  absolute  velocity  of  the 

water  at  exit  from  runner-buckets. 
fy= velocity-head,   corresponding  to   the  velocity  of    the  water 

at  exit  from  draft-tube.     (/= final.) 

Impulse  turbines. — For  Pel  ton  or  impulse  wheel  say  ''impulse 
turbine."  While  Mr.  Lester  A.  Pelton,  who  claims  to  have 
built  such  turbines  as  early  as  1864,  appears  to  have  been 
the  inventor  of  this  type,  yet  there  are  now  so  many  varia- 
tions of  such  turbines  that  a  more  general  name  should  be 
used  for  same. 

InfloTZ  reaction  turbine. — For  Francis  turbine  say  "radial  inward- 
v  flow  reaction"  turbine,  or  simply  "inflow  reaction"  turbine, 
as  this  type  is  usually  understood  by  the  name  Francis  tur- 
bine. While  it  is  not  likely  that  the  term  Francis  turbine 
will  go  out  of  use,  the  term  inflow  reaction  turbine  should 
always  be  used  where  an  exact  expression  is  of  importance, 
as  in  contracts,  for  the  reason  that  Mr.  Francis  also  designed 
outflow  reaction  turbines. 

Internal-feed  turbine. — A  turbine  having  the  guide-ring  inside  of 
the  runner  and  discharging  outward  should  be  called  "internal- 
feed  "  turbine. 

Length  of  draft-tube.— The  distance  from  the  centre  of  the  cross- 
sectional  area  at  the  top  end  of  a  draft-tube  to  the  centre  of 
the  area  at  the  discharge  end,  measured  along  the  centre  line, 
is  called  the  length  of  a  draft-tube,  and  should  also  include 
such  parts  of  the  turbine-case  or  draft  tee  or  elbow  as  have 
approximately  the  same  area  and  shape  as  the  draft-tube. 
However,  when  the  term  is  used  in  connection  with  the  effect 
of  a  flaring  draft-tube  on  the  efficiency,  etc.,  only  that  part 
of  the  length  is  to  be  considered  in  which  the  cross-sectional 


xviii  NOMENCLATURE  AND  SYMBOLS. 

area  is  gradually  and  continually  increasing  toward  the  dis- 
charge end. 

Limit  turbines. — Haenel  turbines,  that  are  action  turbines  with- 
out free  deviation,  should  be  called  " limit"  turbines,  because 
the  jet  of  water  in  the  runner-bucket  is  limited  by  the  back 
of  the  next  vane,  and  also  because  such  turbines  form  the 
limit  between  action  and  reaction  turbines. 
Miscellaneous  symbols. 

Q  =  quantity  of  water  in  cubic  feet  per  second.  The  miner's 
inch,  which  is  measured  in  a  number  of  different  ways 
and  therefore  is  no  exact  unit,  should  be  abandoned  alto- 
gether. 

P= pressure  or  reaction,  in  pounds,  produced  by  a  jet  of  water. 
W= width  or   clear  space  between   crowns  of  runner   at  initial 

or  entrance  rim. 
Wt  =  width  or  clear  space  between  crowns  of  runner  at  terminal 

or  exit  rim. 

e= angle  through  which  a  jet  of  water  is  deflected  by  the  runner- 
buckets. 

n= revolutions  per  minute. 

g= acceleration  of  gravity  =  32. 16  ft.;  V2g=S.Q2. 
Outflow  reaction  turbine. — For  Fourneyron  or  Boy  den  turbine 
say  "radial  outward-flow  reaction"  turbine,  or  else  simply 
" outflow  reaction"  turbine.  It  may  here  be  stated  that  the 
first  turbines  of  Mr.  Fourneyron,  designed  in  1827,  were  out- 
flow action  and  his  later  ones  outflow  reaction  turbines,  and 
the  latter  turbines  are  usually  understood  by  the  name 
Fourneyron  turbine. 

Partial   turbine. — A  turbine  having  guide-buckets  only  on  part 

of  its  circumference,  arranged  in  one,  two,  or  more  groups, 

is  often  known  as  segmental-feed  turbine,  but  should  be  called 

" partial-feed  turbine,"  or  simply  "partial  turbine." 

Penstock. — For  "feeder-pipe  "  or  "water-feeder  "  say  "penstock." 

Penstock  speed. — For  speed  of  water  in  the  cylindrical  or  main 

part  of  the  penstock  say  "penstock  speed." 
Power-water. — The  water  available  under  the  head  utilized  should 
be    called   "power-water,"   corresponding  in  meaning   to  the 
term  live  steam. 


NOMENCLATURE  AND  SYMBOLS.  xix 

Reaction  turbine. — A  turbine  working  with  reaction,  as  the  Jonval, 
Francis,  etc.,  should  be  called  "  reaction  "  turbine. 

Relay. — The  motor  furnishing  the  power  for  actuating  the  regu- 
lating-gates of  a  turbine,  and  usually  controlled  by  a  speed- 
governor,  should  be  called  a  relay.  In  Europe  the  term  servo- 
motor is  used  for  such  auxiliary  machines. 

Return. — To  prevent  overgoverning  or  racing,  a  device  called 
the  "  return  "  is  used  with  modern  turbine-governors,  to  arrest 
the  motion  of  the  regulating-gates  before  moving  beyond  the 
required  position. 

Ridge. — The  radial  edge  dividing  the  buckets  of  impulse  tur- 
bines into  halves  should  be  called  the  "ridge."  The  com- 
mon name  for  it  at  present  is  wedge  or  splitter,  but  in  some 
designs  of  impulse  turbines,  having  double  water- jets,  the 
ridge  is  not  used  for  wedging  into  or  splitting  the  water-jet. 

Right-  and  left-hand  turbine. — When  looking  at  a  radial  inflow 
turbine  or  a  vortex  turbine  in  the  direction  of  the  shaft  and 
facing  the  end  opposite  to  the  discharge  end,  that  is,  looking 
in  the  direction  in  which  the  water  leaves  the  turbine,  the 
turbine  is  a  right-hand  one  if  it  turns  with  the  sun  or  in  the 
direction  of  the  hands  of  a  watch,  and  a  left-hand  one  if  it 
turns  in  the  opposite  direction. 

Runner  diameters,  in  feet. 

D  =  diameter  of  initial  or  entrance  rim  of  runner.  For  impulse? 
turbines  D  is  the  diameter  of  the  bucket  circle,  or  twice 
the  vertical  distance  from  the  centre  line  of  the  jet  of  water, 
or  the  prolonged  centre  line  of  the  nozzle,  to  the  centre 
of  the  runner-shaft. 

Dt  =  diameter  of  terminal  or  exit  rim  of  runner. 

Runner  speeds,  in  feet  per  second. 

v  =  speed  of  runner  at  initial  or  entrance  rim.  For  impulse  tur- 
bines v  is  the  speed  at  the  bucket  circle. 

vt  =  speed  of  runner  at  terminal  or  exit  rim. 

Speed  factor. — The  ratio  of  the  speed  of  the  initial  rim  of  a  runner 
to  the  theoretical  discharge  velocity  of  water  (\/2gH)  under 
the  effective  head  used  by  the  turbine  in  question  should 
be  called  "speed  factor."  This  speed  factor  will  at  once 
show  if  the  turbine  is  an  action,  limit,  or  reaction  turbine, 


XX  NOMENCLATURE  AND  SYMBOLS. 

and  if  the  latter,  with  what  amount  of  reaction  the  turbine 
is  working. 

Speed  variation. — The  performance  of  a  governor  is  usually  given 
by  stating  the  limits  of  variation  within  which  the  governor 
will  keep  the  speed  of  a  turbine;  but  as  there  are  two  ways 
of  expressing  this,  it  should  always  be  stated  what  variation 
is  meant.  Thus  if  the  variation  between  a  maximum  and 
a  minimum  speed  is  meant,  it  should  be  called  "total  speed 
variation,"  and  if  the  variation  either  way  from  the  normal 
speed,  above  and  below,  h  meant,  it  should  be  called  "  speed 
variation  from  the  normal." 

Stop-gate. — This  is  a  gate  or  gate- valve  in  the  penstock  or  pen- 
stock nozzle  located  near  the  turbine,  or  between  penstock 
or  nozzle  and  turbine-case,  or  in  the  turbine-case  itself,  used 
for  shutting  down  the  turbine  and  corresponding  to  the  stop- 
valve  of  a  steam-engine. 

Stop-logs. — These  are  wooden  or  steel  beams  which  form,  when 
placed  in  the  slides  provided  for  them,  a  gate  or  coffer-dam, 
and  are  used  to  keep  out  the  water  from  a  headrace  or  tail- 
race,  turbine-chamber,  etc.,  to  admit  of  inspection  or  repairs. 

Tailwater. — The  water  having  descended  either  through  the  tur- 
bines or  over  the  falls,  should  be  called  "  tail  water,"  corre- 
sponding in  meaning  to  the  term  exhaust  steam. 

Turbine.— For  water-wheel  say  " turbine"  whenever  a  turbine 
is  meant.  For  one,  two,  three,  four,  five,  or  six  turbines  on 
one  shaft  say  single,  double,  triple,  quadruple,  quintuple,  or 
sextuple  turbine.  The  terms  horizontal  or  vertical  turbine 
should  always  mean  a  turbine  on  a  horizontal' or  vertical  shaft, 
and  never  one  revolving  in  a  horizontal  or  vertical  plane,  as 
it  is  now  sometimes  understood. 

Turbine-chamber  and  flume. — For  open  flume  say  "  turbine- 
chamber  "  whenever  a  turbine-chamber  is  meant,  leaving  the 
term  "flume  "  to  mean  a  water-conductor  only,  built  of  wood, 
steel,  or  masonry,  and  carrying  water  not  under  pressure. 

Vanes. —  The  partitions  dividing  the  space  between  the  crowns 
of  the  guide  and  runner  into  the  buckets  and  which,  by  their 
shape  and  angularity,  determine  the  working  of  a  turbine, 
are  usually  called  "vanes."  The  side  against  which  the  water 


NOMENCLATURE  AND  SYMBOLS.  xxi 

exerts  its  pressure,  either  by  its  deflection  or  by  deflection 
and  reaction,  and  which  side  is  nearly  always  concave,  is  the 
"face,"  the  other  side  the  "back,"  of  the  vane. 
Vortex  turbines. — Turbines  of  the  American  type,  in   which  the 
water  when  entering  the  runner-buckets,  flows  radially  inward, 
then  axially  and  leaves  the  bucket  at  a  slant,  between  the 
axial    and   radial    outward-flow  direction,   are   usually   called 
"  vortex  "  turbines. 
Water-speeds,  in  feet  per  second, 

c  =  speed  of  water  at  exit  from  guide-buckets,  and  at  the  same 
time  the  absolute  entrance  speed  of  water  in  runner-buckets. 
ce  =  initial  or    entrance  speed  of  water   in  runner-buckets,  rela- 
tive to  the  buckets. 
ct  =  terminal  speed  of  w^ater  in    runner-buckets,  relative  to  the 

buckets. 

ca  =  absolute  speed  of  water,  that  is,  the  speed  relative  to  a  sta- 
tionary object,  at  exit  from  runner-buckets. 

Cb= initial  speed  of  water  in  draft-tube,  that  is,  the  speed  of 
water,  while  entering  the  upper  end  of  the  draft-tube. 
(b  =  beginning.) 

c/= speed  of  water  at  exit  from  lower  end  of  draft-tube.     (/=  final.) 
This  speed,  being  of  great  importance  in  connection  with 
the  efficiency  and  proper  working  of  a  turbine,  should  be 
called  "draft-tube  speed." 
Wing-gate. — For  butterfly-gate  say  "wing-gate." 

DRAWINGS. 

It  would  also  be  well  to  adopt  some  uniform  names  for  sec- 
tions and  views  of  turbines,  and  the  writer  would  suggest  the 
following : 

For  horizontal  turbines:  A  vertical  section  through  the  centre 
line  of  or  parallel  to  the  shaft  is  a  "longitudinal  "  section,  and 
a  vertical  section  at  right  angles  to  the  shaft  is  a  "cross  "-sec- 
tion. A  view  looking  at  right  angles  to  the  shaft  is  a  "side  " 
elevation,  and  looking  in  the  direction  of  the  shaft  an  "end  " 
elevation.  The  names  plan  and  horizontal  section  cannot  well 
be  misapplied. 


xxii  NOMENCLATURE  AND  SYMBOLS. 

For  vertical  turbines:  A  section  through  the  centre  line  of  or 
parallel  to  the  shaft  is  a  "  vertical  "  section,  and  a  section  at 
right  angles  to  the  shaft  is  a  "  horizontal  "  section.  A  view 
looking  at  right  angles  to  the  shaft  is  an  "  elevation/'  and 
looking  in  the  direction  of  the  shaft  a  "plan." 


CIVIL  ENGINEERING 

11.  o!  C. 
ASSOCIATION  LIBRARY 


PAET  I. 

MODERN  TURBINE  PRACTICE. 


CHAPTER  I. 
TURBINE  PRACTICE  IN  EUROPE. 

Turbine  Development  in  Europe. — The  turbine  may  be  called 
a  theoretical  invention,  as  it  is  one  of  the  few  machines  which 
have  been  invented  as  the  direct  outcome  of  mathematical  inves- 
tigation, and  not  by  experiment,  like  the  steam-engine  and  others, 
and  its  further  evolution  in  Europe  has  always  been  based  on 
theory.  In  America,  however,  turbine  construction  has  been 
developed  almost  solely  by  experiment. 

Although  most  of  the  early  turbines  were  of  the  radial-flow 
type,  the  axial-flow  turbine  soon  became  the  standard  type  of 
European  builders,  and  remained  so  until  a  few  years  ago,  while 
the  radial-flow  turbine  was  rarely  used,  except  for  partial  turbines 
working  under  high  heads. 

An  interesting  example  of  the  axial-flow  type  is  the  turbine 
at  the  water-works  of  Geneva,  Switzerland,  shown  in  Figs.  1  and  2. 
This  turbine  drives  two  plunger-pumps  with  vertical  crank-shaft, 
and  develops  from  50  to  100  H. P.  under  a  head  varying  between 
16J  and  35J  ins.,  running  from  9  to  16  revolutions  per  minute, 
and  using  from  530  to  706  cu.  ft.  of  water  per  second.  The  siphon- 
feeder  was  employed  to  save  tailrace  excavation,  which  is  in 
hard  rock,  as  without  the  siphon  the  turbine  would  have  to  be 
set  much  lower.  The  efficiency  is  naturally  low  for  such  small 


MODERN  TURBINE  PRACTICE. 


V\\\\\\\\\\\\\\\\\N 


FIGS.  1  and  2. — 50-100-H.P.  Turbine  at  the  Water-works  of  Geneva,  Swit- 
zerland.    Built  by  Girard  &  Gallon,  Paris,  France. 


TURBINE  PRACTICE  IN  EUROPE.  3 

heads,  as  the  mechanical  losses  are  great  in  proportion  to  the 
power  developed.  This  turbine  and  pumps,  with  a  head  of  16^  ins., 
have  a  combined  efficiency  of  48%,  or  say  58%  for  the  turbine 
alone.1 

This  turbine  was  designed  by  Mr.  Girard  and  therefore  is  an 
action  turbine.  At  present  vertical-inflow  reaction  turbines  are 
always  used  for  very  low  heads. 

Axial-flow  turbines  are  simple  and  cheap,  but  no  satisfactory 
way  of  regulating  their  speed  could  be  found,  and  with  the  advent 
of  electrical  transmission,  requiring  close  regulation  and  higher 
speeds,  builders  cast  about  for  a  new  type  of  turbine.  A  great 
variety  of  new  designs  were  then  brought  forward,  and  while  as 
yet  none  have  been  definitely  and  generally  adopted,  some  of 
the  designs  used  by  the  most  progressive  builders  are  certain  to 
be  soon  recognized  as  the  coming  standard  types.  These  designs 
are: 

For  low  heads,  say  up  to  20  ft. :  Radial  inward-flow  reaction 
turbines  with  vertical  shafts,  the  foundation  masonry  usually  form- 
ing the  turbine-case,  draft-tubes  being  frequently  employed.  (See 
Figs.  19,  20,  22,  and  23.) 

For  medium  heads,  say  from  20  to  300  ft.:  Radial  inward- 
flow  reaction  turbines  with  horizontal  shafts  and  concentric  or 
spiral  cast-iron  cases  with  draft-tubes.  (See  Figs.  26  to  41.) 

For  high  heads,  say  above  300  ft.:  Radial  outward-flow,  full- 
or  partial-action  turbines,  with  horizontal  shafts  and  cast-  or 
wrought-iron  cases,  frequently  with  draft-tube.  (See  Figs.  42 
to  48.) 

A  modified  impulse  turbine  has  of  late  been  gaining  in  favor, 
and  it  is  most  likely  that  the  type  ultimately  adopted  for  high 
heads  will  be  a  combination  of  the  best  points  of  the  partial- 
action  turbine  and  the  impulse  turbine.  (See  Figs.  49  to  56.) 

As  the  axial-flow  turbine  has  practically  been  abandoned  > 
the  following  refers  to  radial-flow  turbines  only. 

Of  all  European  countries,  Switzerland,  having  many  excel- 
lent water-powers  and  producing  no  coal  whatever,  ranks  high- 
est in  progressive  turbine-building,  being  closely  followed  by 

1  Meissner.     Hydraulische  Motoren,  vol.  2,  p.  588. 


MODERN  TURBINE  PRACTICE. 

Germany,  Austria,  and  Italy.  France,  although  the  native  country 
of  the  turbine,  and  rich  in  water-powers,  has  advanced  little  during 
the  last  ten  years,  except  that  some  builders  are  closely  copying 
American  turbines,  such  as  the  Hercules.  Most  of  the  turbines 
installed  in  important  French  plants  are  supplied  by  Switzerland. 

Mr.  Prasil,  professor  of  the  Polytechnikum  in  Zurich  and 
one  of  the  prize- judges  for  the  turbines  at  the  Paris  exhibition 
in  1900,  says  in  his  report:1  "Modern  French  turbine-building 
at  the  exhibition  was  characteristically  shown  by  the  Hercules 
type.  Besides  this,  only  old  types  were  to  be  seen.  Little  atten- 
tion seems  to  have  been  paid  by  French  designers  to  the  progress 
in  turbine-building  made  in  Central  Europe,  especially  to  the 
solution  of  the  problem  of  regulation." 

However,  French  builders  have  recognized  the  fact  that  the 
same  pattern  of  turbine  can  work  economically  only  under  a 
certain  range  of  heads.  For  example,  one  of  the  largest  manu- 
facturers of  turbines  of  the  Hercules  type  2  offers  four  series  of 
pattern,  to  suit  heads  as  follows:3  Series  1,  3.25  to  10  ft.; 
Series  2,  10  to  25  ft.;  Series  3,  25  to  40  ft.;  Series  4  (special), 
40  to  108  ft. 

The  application  of  the  laws  of  hydraulics  to  the  action  of  water 
in  simple  radial-  or  axial-flow  turbines  being  well  understood  since 
early  in  the  nineteenth  century,  the  highest  possible  hydraulic 
efficiencies  could  be  calculated  for  the  different  types  of  turbines, 
and  multiplying  these  values,  which  vary  between  0.80  and  0.90 
for  the  usual  designs,  by  the  highest  possible  mechanical  effi- 
ciency of  the  turbine  under  consideration,  the  limit  of  the  pos- 
sible total  efficiency  is  found.  This  limit,  which  may  be  con- 
sidered to  lie  between  0.75  and  0.85  for  practical  working  types, 
has  been  reached,  or  very  closely  approached,  with  one  half  to 
full  discharge  at  least,  by  the  regular  turbines,  such  as  the  best 
European  builders  have  turned  out  during  the  last  twenty  years 
or  more.  Their  present  efforts  are,  therefore,  to  make  the  tur- 
bine a  complete  and  self-contained  machine,  to  improve  the  details, 
such  as  step-  and  journal-bearings,  regulating-gates  and  their 

1  Schweiz.  Bauz.,  Feb.  16,  1901,  p.  74. 

2  Singrun  Freres,  Epinal,  France. 

3  Mueller.     Francis-Turbinen,  p.  273. 


TURBINE   PRACTICE  IN  EUROPE.  5 

rigging,  oiling  of  bearings  under  water,  etc.,  to  raise  the  speed 
for  turbines  working  under  low  heads,  and,  as  has  been  the  endeavor 
for  a  long  time,  to  improve  the  efficiency  of  reaction  turbines 
when  running  with  only  a  fraction  of  their  full  discharge. 

Builders  also  have  realized  the  expense  involved  in  making 
separate  patterns  for  every  turbine  built,  and  all  the  large  manu- 
facturers have  now  lists  of  standard  sizes,  furnishing  specially 
designed  turbines  only  when  the  occasion  requires  it. 

Present  Turbine  Practice  in  Europe. — The  principal  features 
only  of  the  present  European  practice  are  here  dealt  with,  while 
examples  of  European  turbines  will  be  described  later  on. 

The  question  of  efficiency  with  part  loads  has  been  so  well 
solved  for  action  turbines  that  further  improvements  are  not 
to  be  expected.  Efficiencies  of  70  %  for  0.2  discharge  to  80% 
for  full  discharge  are  the  common  practice,  and  these  results 
have  been  reached  by  very  simple  means.  With  full  turbines 
an  ordinary  cylinder  gate  is  used,  as  shown  hi  Figs.  42  to  44, 
reducing  the  outflow-openings  of  all  guide-buckets  equally,  in 
proportion  to  the  decrease  in  power  developed,  while  with  par- 
tial turbines  a  slide  is  employed,  as  shown  in  Figs.  45  and  46,  which 
closes  the  outflow-opening  of  one  guide-bucket  after  the  other 
as  the  load  on  the  turbine  is  reduced. 

Greater  difficulties,  however,  are  met  with  when  it  is  attempted 
to  regulate  reaction  turbines  so  as  to  show  high  efficiencies  with 
part  loads.  The  simplest  means  are^in  this  case  the  most  waste- 
ful, and  have  practically  been  abandoned,  but  may  be  mentioned 
here,  viz.,  the  throttling  of  .the  water  in.  the  inlet-pipe  or  in  the 
draft-tube  by  wing-gates %  (see  Figs.  57  and  58),  or  at  the  lower 
end  of  the  draft-tube  by  a  cylinder  gate,  closing  the  annular 
space  between  the  draft-tube  and  the  bottom  of  the  turbine-pit. 
For  high  heads  and  very  long  penstocks  a  by-pass  was  used  in 
connection  with  the  throttle-valve. 

The  three  methods  of  regulating  reaction  turbines  most  widely 
tised  in  Europe  at  the  present  time  are  as  follows: 

1.  The  cylinder  gate.  The  width  of  the  guide-  and  runner- 
buckets,  or  the  distance  between  the  crowns,  is  divided  into 
two  or  more  spaces  by  additional  crowns,  thus  forming  two.  or 
more  turbines,  which  are  regulated  by  one  common  cylinder  gate. 


6  MODERN   TURBINE  PRACTICE. 

Thus  a  triple — or  three-story — turbine,  when  working  with  one- 
third  or  two-thirds  gate-opening,  has  one  or  two  turbines  working 
with  full  gate  and  full  gate  efficiency,  while  the  two  turbines  or 
one  remaining  are  shut  off  entirely. 

The  cylinder  gate  in  nearly  all  cases  works  between  the  guides 
and  runner.  As  an  example  of  recent  design  may  be  mentioned 
the  700-H.P.  horizontal-inflow  turbine  built  by  Siccard,  Pictet 
&  Co.,  Geneva,  Switzerland,  for  a  power  plant  in  southern  France.1 
These  turbines  have  a  width  of  buckets  of  nearly  30  ins.,  divided, 
into  five  stories,  all  regulated  by  a  single  gate.  The  5500-H.P.  tur- 
bines in  power-house  No.  1  of  the  Niagara  Falls  Power  Co.,  at 
Niagara  Falls,  N.  Y.,2  are  examples  of  three-story  turbines  with 
the  cylinder  gate  on  the  discharge  side  of  the  runner.  Turbines 
with  a  width  of  buckets  not  sufficient  to  permit  the  use  of  addi- 
tional crowns  should  not  be  regulated  by  cylinder  gates,  as  the 
economy  is  poor  with  part  loads. 

2.  The  Register  Gate.  A  part  of  each  of  the  vanes  which  form 
the  guide-buckets  is  separate  from  the  rest  of  the  vane,  being 
attached  at  each  crown  to  a  movable  ring,  so  that  by  rotating 
these  rings  the  size  of  each  of  the  clear  openings  between  the 
vanes  can  be  altered  simultaneously  in  accordance  with  altera- 
tions in  the  load  of  the  turbine.  The  movable  part  of  the  vanes 
may  be  either  at  the  entrance  or  at  the  discharge  side  of  the  guide- 
buckets.  The  former  plan  is  now  rarely  used,  as  the  shape  of 
the  bucket  is  too  much  distorted  when  the  gate  is  partly  closed,3 
With  the  gate  at  the  discharge  side  the  shape  of  the  bucket  is 
much  better  maintained,  and  such  an  arrangement  is  used  by 
many  builders.  Figs.  28  and  29  show  such  a  gate.  A  great  im- 
provement over  the  ordinary  register  gate  is  the  Zodel  gate.  Here 
also  the  discharge  end  of  the  vanes  is  movable,  but  a  steel  plate 
is  bolted  to  the  back  of  the  stationary  part  of  each  vane,  thus 
retaining  the  proper  shape  of  at  least  one  side  of  the  buckets 
at  all  positions  of  the  gate.  In  Figs.  3  and  4  the  Zodel  gate  is 
shown  in  three  positions,  viz.,  fully  and  half  open  and  closed. 
When  fully  closed,  the  movable  part  of  the  vanes  forces  the  steel 

1  Zeitsch.  d.  V.  deutsch.  Ing.,  Nov.  16,  1901,  p.  1633. 

2  Wood.     Turbines,  Fig.  57. 

JSchweiz.  Bauz.,  Feb.  16,  1901,  p.  72,  Fig.  14. 


TURBINE  PRACTICE  IN  EUROPE.  7 

plates  slightly  outward,  and  these  steel  plates,  acting  as  springs, 
are  thus  insuring  a  tight  joint.  The  turbines  shown  in  Figs.  25, 
30,  31,  36,  and  37  are  regulated  by  Zodel  gates. 

3.  The -Wicket  Gate.  The  whole  guide-vane  swings  on  pivots 
so  located  as  to  balance  the  vane  as  nearly  as  it  is  possible  in 
every  position.  Here  also  all  the  vanes  move  and  thus  alter 
the  size  of  the  discharge-openings  of  the  buckets  simultaneously. 
Such  gates  maintain  the  correct  shape  of  the  guide-buckets  at 
part  gate  opening  better  than  any  other  gate.  The  most  widely 


PIGS.  3  and  4. — Zodel  Register  Gate.     Gate  shown  in  open,  half-closed,  and 

closed  position. 

used  design  is  the  Fink  gate,  which  is  shown  in  connection  with 
the  turbines  illustrated  in  Figs.  26  and  27  and  32  to  34. 

A  regulation  which  may  be  called  either  a  register  or  a  wicket 
gate  is  used  for  the  turbine  shown  in  Figs.  40  arid  41,  and  is  also 
employed  for  the  large  turbines  at  Beznau.  (Fig.  19.)  This 
gate  has  part  of  each  vane  movable,  which  part  is  located  on 
the  entrance  of  the  buckets  and  both  swings  and  moves  inward 
at  the  same  time,  the  inner  ends  of  the  movable  part  of  one  vane 
and  the  stationary  part  of  the  next  vane  meeting  when  the  gate 
is  closed.  This  gate  also  maintains  a  good  bucket  shape,  except 
for  very  small  gate-openings. 


8  MODERN  TURBINE  PRACTICE. 

The  ideal  regulation  of  reaction  turbines  would  be  the  simul- 
taneous altering  of  the  size  of  all  the  clear  openings  of  both  the 
guide-  and  the  runner-buckets,  in  accordance  with  alterations  of 
the  load,  and  without  changing  the  curvature  or  shape  of  the 
buckets.  This  could  be  attained  by  making  one  crown  of  each, 
the  guide  and  the  runner,  movable,  so  that  the  size  of  the  bucket- 
openings  could  be  varied  by  varying  the  distance  between  the 
crowns,  but  all  attempts  to  carry  this  out  in  practice  have  so 
far  failed. 

However,  even  with  the  imperfect  gate  arrangements,  Euro- 
pean builders  now  commonly  realize  the  following  efficiencies 
with  reaction  turbines:1 

Discharge 0.2          0.3          0.4          0.5          0.6 

Efficiency 60%         70%         76%         79%         80% 

Discharge 0.7          0.8          09  10 

Efficiency 81%         82%         81%         80% 

It  should  be  noted  here  that  the  highest  efficiency  of  reaction 
turbines  is  usually  found  to  be  at  about  0.8  of  the  full  gate  dis- 
charge, although  such  turbines  may  be  designed  to  give  their 
maximum  efficiency  at  any  desired  discharge. 

Action  turbines  must,  for  good  efficiency,  work  in  the  air; 
that  is,  above  and  clear  of  the  tailwater.  Therefore,  to  enjoy 
the  advantages  of  a  draft-tube  with  this  class  of  turbines,  they 
are  now  furnished  with  an  air  admission-valve,  which  automati- 
cally regulates  the  water  level  in  the  turbine-case  or  draft-tube, 
so  as  to  keep  it  just  below  and  clear  of  the  turbine-runner.  (See 
Figs.  42  to  46.) 

Outward-flow  turbines  can  either  be  designed  to  have  no  end 
thrust  whatever,  and  turbines  on  horizontal  shafts  are  usually 
arranged  in  this  manner  (see  Figs.  42  to  48),  or  to  have  any  desired 
amount  of  end  thrust,  up  to  the  limit  set  by  the  head  of  the  water 
and  the  size  of  the  turbine.  Such  end  thrust  is  often  employed 
to  support  the  weight  of  the  rotating  parts  of  turbines  on  ver- 
tical shafts.  As  an  example  may  be  mentioned  the  5500-H.P. 
turbines  at  Niagara  Falls,  N.  Y.,  where  the  lower  turbine  of  each 
pair  has  no  end  thrust,  while  the  upper  one  has  an  upward  thrust, 

1  Zeitsch.  d.  V.  deutsch.  Ing.,  Nov.  22,  1902,  p.  1790 


TURBINE  PRACTICE  IN  EUROPE.  0 

which  carries  the  runners,  shaft,  and  rotating  field,  weighing 
together  about  80  tons.  This  large  weight  is  practically  floating 
on  the  water,  and  the  easy  working  of  these  turbines  is  well 
illustrated  by  the  fact  that  without  load  they  will  run  at  a 
speed  of  40  revolutions  per  minute,  with  the  turbine-gates 
entirely  closed  and  only  using  the  water  which  leaks  through 
the  small  clearance  between  the  runners  and  the  gates,  which 
clearance  is  only  &  in.  If  it  is  desired  to  stop  the  turbines 
without  closing  the  head-gates,  a  brake  has  to  be  applied  to 
bring  the  turbines  to  rest.1 

Single  inward-flow  reaction  turbines,  and  to  a  much  smaller 
degree  certain  types  of  inward-flow  action  turbines,  present  great 
difficulties  in  taking  care  of  the  end  thrust,  especially  trouble- 
some in  connection  with  high  heads.  This  difficulty  has  been 
successfully  overcome  by  European  builders  by  two  different 
means,  used  according  to  the  conditions.  These  means  are  the 
following : 

1.  The  Thrust  Piston.  This  arrangement  is  principally  used 
for  vertical-inflow  turbines  and  takes  the  thrust  of  both  the 
action  of  the  water  and  the  weight  of  the  rotating  parts.  As  a 
conspicuous  example,  one  of  the  5500-H.P.  turbines  for  power- 
house No.  2  of  the  Niagara  Falls  Power  Co.  is  shown  in  Fig.  5.2 

This  is  a  single  vertical  inward-flow  reaction  turbine  in  an 
approximately  spherical  case,  the  turbine  being  at  the  top,  and 
the  shaft  is  extended  downward  into  the  draft-tube  and  carries 
the  thrust  piston  at  its  lower  end,  at  the  apex  of  the  Y  branches 
of  the  draft-tube.  The  piston  is  grooved  to  reduce  the  leakage, 
and  the  cylinder  in  which  the  piston  rotates  has  a  renewable 
lining.  The  pressure  water  acting  at  the  lower  side  of  the  pis- 
ton is  taken  directly  from  the  headrace,  screened  to  keep  out 
dirt  and  gritty  matter,  and  carried  to  the  cylinder  by  an  inde- 
pendent pipe.  The  upper  side  of  the  piston  is  subjected  to  the 
partial  vacuum  or  suction  in  the  draft-tube.  The  rotating  parts, 

1  Coleman  Sellers.  The  Power  Station  at  Niagara  Falls.  Trans.  Anv 
Soc.  M.  E.,  1898.  Also  reprint  in  Engineering,  London,  Jan.  20,  p.  91, 
Jan.  27,  p.  128,  and  Feb.  3,  p.  160,  1899. 

2Zeitsch.  d.  V.  deutsch.  Ing.,  Aug.  31,  1901,  p.  1239;  also  an  abstract 
in  Engineering  Record,  Nov.  23,  1901,  p.  500. 


MODERN  TURBINE  PRACTICE. 


l 


FIG.  5. — 5500-H.P.  Turbine  for  Power-house  No.  2.  of  the  Niagara  Falls 
Power  Co.,  Niagara  Falls,  N.  Y.  Built  by  Escher,  Wyss  &  Co.,  Zurich, 
Switzerland. 


TURBINE  PRACTICE  IN  EUROPE.  11 

viz.,  the  runner,  shaft,  and  revolving  field  of  the  dynamo,  have 
a  total  weight  of  71  tons,  and  of  this  weight  the  piston  carries  from 
66  tons  with  full  gate-opening  to  77  tons  with  the  gate  nearly  closed, 
the  difference  between  weight  and  upward  thrust  being  taken 
by  a  collar-1  eirma;  above. 

The  variation  in  effective  upward  thrust  with  different  gate- 
openings  is  principally  due  to  the  variation  in  the  pressure  above 
the  turbine-runner  and  the  variation  in  the  amount  of  vacuum 
in  the  draft-tube.  With  full  gate-opening,  water  under  pressure 
will  be  forced  through  the  clearance  into  the  space  above  the  runner, 
while  the  fan-wheel  action  of  the  runner  tends  to  force  the  water 
outward,  thus  creating  a  pressure  above  the  runner.  With  the 
gate  nearly  closed,  practically  the  same  vacuum  will  exist  above 
the  runner  as  in  the  draft-tube.  This  is  owing  to  the  fact  that 
with  very  small  gate-openings  the  water  in  a  reaction  turbine 
works  with  action  only,  as  will  be  explained  when  considering 
the  effect  of  speed-regulating  gates. 

With  the  amount  of  water  passed  by  the  gate-opening  decreas- 
ing, the  velocity  with  which  the  water  leaves  the  lower  end  of 
the  draft-tube  decreases  in  the  same  proportion  and  the  vacuum 
therefore  increases,  as  will  be  explained  under  draft-tubes. 

The  turbine  seen  in  the  power-house  cross-section,  Fig.  20,  is 
also  provided  with  a  thrust-piston,  carrying  22  tons  of  the  weight 
of  the  revolving  parts,  but  here  the  turbine  is  at  the  bottom  of 
the  case — in  other  words,  hangs  on  the  shaft — while  the  thrust- 
piston  is  at  the  top  and  the  water-pressure  in  the  case  acts  directly 
on  its  lower  surface.  The  water  leaking  past  the  piston  into 
the  space  above  is  led  into  the  draft-tube  by  a  waste-pipe,  as 
shown  in  Fig.  20,  thus  reducing  the  pressure  above  the  piston 
to  that  in  the  draft-tube.  The  piston  area  may  be  made  larger 
than  required  for  balancing  the  thrust  and  by  closing  the  valve 
in  above-mentioned  waste-pipe  more  or  less,  the  pressure  above 
the  piston  is  increased  or  decreased,  and  the  remaining  total  upward 
pressure  can  thus  be  closely  regulated. 

2.  The  Thrust-chamber.  This  arrangement  is  principally  used 
to  take  the  end  thrust  of  horizontal  inflow  turbines  and  consists 
of  an  annular  chamber,  formed  by  the  cast-iron  turbine-case 
and  open  towards  the  runner,  which  revolves  in  front  of  it,  a 


12  MODERN   TURBINE  PRACTICE. 

shown  in  Figs.  30  and  34.  The  water-pressure  in  the  chamber 
is  supplied  by  a  pipe,  the  pressure  being  regulated  by  a  valve 
in  that  pipe.  The  arrangement  of  the  pipe  connection  is  in  accord- 
ance with  the  class  of  turbine  employed  and  therefore  two  differ- 
ent cases  have  to  be  considered. 

(a)  The  Inflow  Reaction  Turbine.  Here  the  water  is  under 
pressure  while  passing  the  clearance  and  will  therefore  leak  into 
the  space  back  of  the  runner,  that  is,  between  the  runner-disk 
and  the  head  of  the  turbine-case  and  into  the  thrust-chamber. 
Opposed  to  this  pressure  is,  at  the  back  of  the  runner-disk,  the 
fan-wheel  action  of  the  latter  and  the  force  required  to  press  the 
water  through  the  openings  in  the  disk.  In  the  thrust-chamber 
pressure  is  opposed  by  the  fan-wheel  action  of  the  runner  and 
the  force  required  to  press  the  water  through  the  clearance  space 
at  the  inner  edge  of  the  chamber.  As  a  rule,  the  total  pressure 
back  of  the  runner-disk  will  exceed  the  total  pressure  due  to  the 
leakage  into  the  chamber,  and  therefore  pressure  water  has  to 
be  admitted  to  the  latter,  yet  owing  to  differences  in  clearance- 
spaces,  in  shape  or  roughness  of  the  back  and  chamber  side  of 
the  runner  and  other  minor  causes,  the  total  pressure  in  the  thrust- 
chamber  may  rise  above  the  total  pressure  at  the  back  of  the 
runner,  and  to  relieve  this  pressure  the  chamber  is  also  connected 
to  the  draft-tube,  as  shown  in  Fig.  30. 

•  (b)  The  Inflow  Action  Turbine  with  Limited  Buckets.  Here  the 
water  is  not  under  pressure  while  passing  the  clearance  and  no 
water  will  be  forced  into  the  thrust-chamber,  but  the  fan-wheel 
action  of  the  runner  may  draw  water  into  the  space  back  of  the 
runner  and,  throwing  it  outward,  create  a  pressure,  which  is  bal- 
anced by  admitting  pressure  water  to  the  thrust-chamber.  (See 
Fig.  34.) 

By  means  of  the  valve  in  the  pipe  connecting  the  thrust-chamber 
with  the  pressure  water  and  draft-tube  or  the  pressure  water 
only,  the  end  thrust  can  be  so  regulated  that  the  shaft  will  press 
against  the  step-bearing  with  just  enough  force  to  prevent  any 
end  motion. 

The  valves  for  regulating  the  pressure  in  the  space  back  of 
the  runner  and  back  of  the  thrust-piston  or  in  the  thrust-chamber 
are  operated  by  hand,  but  it  may  prove  of  advantage  to  use  auto- 


TURBINE  PRACTICE  IN  EUROPE.  13 

matic  pressure-regulating  valves  instead,  maintaining  a  fixed  dif- 
ference in  pressure  in  these  two  spaces. 

It  has  been  attempted  to  regulate  the  pressure  in  the  thrust- 
chamber  and  back  of  the  runner  by  making  the  width  of  the 
clearances  between  runner  and  guides  and  inner  edge  of  thrust- 
chamber  and  between  runner  and  guides  or  turbine-case  in  proper 
proportion,  but  as  these  clearances  should  not  be  wider  than 
from  ^  to  ^  in.  and  will  wear  larger  and  wear  unequally,  this 
plan  has  not  met  with  any  success. 

For  turbines  having  runners  of  such  a  shape  as  not  to  per- 
mit the  use  of  the  thrust-chamber,  as  for  example  the  American 
or  vortex  turbine  (see  Fig.  9,  also  Fig.  26),  the  thrust-piston 
can  always  be  used  instead,  having  the  runner  on  one  end  and 
the  piston  on  the  other  end  of  the  case. 

The  use  of  wood  with  water  lubrication  for  bearings  and  steps 
located  under  water  has  been  abandoned  altogether  by  European 
manufacturers,  and  metal  bearings  and  steps  with  forced  oil  lubri- 
cation are  employed  instead,  using  a  pressure  and  return  pipe 
for  circulating  the  oil.  The  pipe  connections  to  the  bearing  above 
the  runner  and  the  one  below  the  thrust-piston  aTe  shown  in  the 
illustration  of  the  Niagara  Falls  turbines,  Fig.  5,  and  similar  con- 
nections are  shown  in  the  illustration  of  a  horizontal  double  tur- 
bine, Fig.  25. 

In  general  it  may  be  said  that  European  builders  have  brought 
out  and  perfected  a  number  of  turbine  types,  which  have  enabled 
them  to  meet  any  reasonable  conditions,  and  to  predetermine 
and  guarantee  a  high  efficiency  in  all  cases;  for  the  small  tur- 
bine of  a  few  horse-powers  as  well  as  for  those  of  5500  H.P.  at 
Niagara  Falls,  and  for  the  head  of  16J  ins.  used  at  G.eneva,  Switzer- 
land, as  well  as  for  the  highest  heads,  such  as  those  used  at  Ver- 
nayaz,  also  in  Switzerland,  where  the  six  turbines  at  the  electric 
power  station  are  developing  1000  H.P.  each  under  a  head  of 
1640  ft.  One  of  these  turbines  is  shown  in  Figs.  47  and  48. 

Turbine-pumps. — The  reversed  turbine  or  turbine  centrifugal 
pump,  like  the  turbine  itself,  was  evolved  by  theoretical  inves- 
tigations. 

Turbine  designers  reasoned  correctly  that  when  a  turbine 
with  a  certain  head  and  quantity  of  water  gives  a  certain  horse- 


14  MODERN  TURBINE  PRACTICE. 

power  and  number  of  revolutions,  then  a  similar  turbine,  being 
driven  from  some  outside  power  at  the  same  speed  but  in  oppo- 
site direction,  will  act  as  a  pump,  elevating  the  same  quantity 
of  water  to  the  same  height  and  requiring  the  same  horse-power 
as  was  developed  by  the  machine  when  used  as  a  turbine.  Of 
course,  allowance  has  to  be  made  in  practice  for  the  losses  in 
both  the  turbine  and  the  pump. 

Such  turbine-pumps  are  of  recent  date  only,  yet  some  remark- 
able results  have  been  obtained  with  them. 

While  theoretically  all  turbines  could  be  reversed,  the  radial 
Inward-flow  type  was  naturally  chosen,  and  the  buckets  and  other 
water  passages  were  somewhat  modified  in  shape,  as  the  direction 
in  which  the  water  flows  through  the  pump  is  opposite  to  that 
in  which  it  flows  through  the  turbine  The  turbine-runner  acts 
as  the  fan-wheel  of  the  pump  and  the  guide-buckets  convert  the 
speed  of  the  water  imparted  to  it  by  the  fan-wheel  into  pressure, 
and  it  is  this  application  of  the  guide-buckets  which  constitutes 
the  great  improvement  and  permits  the  turbine-pump  not  only 
to  work  economically  against  heads  considerably  higher  than 
•could  ever  be  attempted  with  the  ordinary  centrifugal  pump,  but 
also  to  give  a  much  better  efficiency  than  can  be  obtained  with 
the  ordinary  pump  even  under  low  heads. 

For  comparison  it  should  be  stated  here  that  the  ordinary 
centrifugal  pump  shows  a  maximum  efficiency  with  a  lift  of  about 
17  ft.,  this  efficiency  being  between  50%  and  65%,  according 
to  the  shape  of  the  fan-wheel  and  case  and  the  size  of  the  pump. 

As  another  case  of  the  reversibility  of  turbine  and  centrifugal 
pump  may  be  mentioned  the  reversed  centrifugal  pump,  that  is, 
the  radial  inward-flow  turbine  without  guide-buckets,  which  has 
repeatedly  been  brought  out  by  manufacturers,1  but,  like  the 
ordinary  centrifugal  pump;  has  always  given  such  poor  efficiencies 
even  with  low  heads  and  a  rapid  further  decrease  in  efficiency 
with  increasing  heads,  the  same  as  the  centrifugal  pump,  that 
such  turbines  have  never  been  used  to  any  extent. 

A  number  of    turbine-pumps,  shown  in  Figs.  6  and  7,  were 

1  An  example  was  the  turbine  of  the  Chase  Manufacturing  Co.,  Orange, 
Mass.,  shown  and  tested  at  the  Philadelphia  Exhibition,  1876. 


TURBINE  PRACTICE  IN  EUROPE. 


15 


recently  built  and  tested  in  Switzerland,  each  having  four  fan- 
wheels  in  one  case,  arranged  in  series;   that  is,  the  first  fan-wheel 


discharges  into  the  suction  of  the  second  one,  and  so  on,  the  water 
successively  passing  through  all  wheels.  These  fan-wheels  have 
a  diameter  of  20  ins.,  and  with  890  revolutions  deliver  1010  U.  S. 


16  MODERN  TURBINE  PRACTICE. 

gallons  of  water  per  minute  against  a  head  of  428  ft.,  which  is 
equal  to  107  ft.  of  head  for  a  pump  with  single  fan-wheel,  and 
give  an  efficiency  of  76%,  certainly  a  great  advance  in  the  con- 
struction of  centrifugal  pumps.1 

As  has  been  said,  the  turbine-pump  is  only  of  recent  date,  and 
it  is  safe  to  predict  that  its  efficiency  will  be  brought  up  to  that 
of  the  turbine,  viz.,  80  to  82%,  at  least  for  heads  up  to  100  ft. 

It  is  also  to  be  expected  that  by  the  use  of  regulating  gates, 
such  as  are  employed  for  turbines  to  change  the  openings  of  the 
guide-buckets^  the  turbine-pump  may  be  made  to  discharge  at 
will  any  quantity  of  water,  from  its  full  capacity  to  a  small  frac- 
tion thereof,  without  change  of  speed  or  a  serious  reduction  in 
efficiency.2 

1  Zeitsch.  d.  V.  deutsch.  Ing.,  Nov.  2,  1901,  p.  1549;  also  an  abstract  in 
Engineering  News,  Jan.  23,  1902,  p.  66.     See  also  Zeitsch.  d.  V.  deutsch. 
Ing.,  Oct   12,  1901,  p.  1448. 

2  Turbine-pumps  are  discussed  in  Mr.  Elmo  G.  Harris's  paper,  "  Theory  of 
Centrifugal  Pumps  and  Fans:    Analysis  of  Their  Action,  with  Suggestions 
for  Designers,"  read  before  the  Am.  Soc.  C.  E.,  Sept.  16,  1903. 


CHAPTER  II. 
TURBINE  PRACTICE  IN  AMERICA. 

Turbine  Development  in  America. —  In  the  United  States 
the  development  of  the  turbine  has  been  entirely  different  from 
that  in  Europe.  In  1834  Mr.  Fourneyron,  a  French  engineer, 
had  brought  out  the  radial  outward-flow  turbine  known  under 
his  name,  and  hi  1840  Mr.  U.  A.  Boyden,  of  Massachusetts,  com- 
menced to  study  and  to  improve  upon  this  type.  Mr.  Fourney- 
ron's  diffuser  was  also  introduced  in  America  by  Mr.  Boyden, 
and  is  therefore  usually  known  as  Boyden  diffuser.  It  should 
here  be  stated  that  the  now  obsolete  diffuser  was  the  forerunner 
of  the  conical  draft-tube  of  the  present  day,  and  the  same  prin- 
ciples .are  underlying  the  action  of  both. 

Mr.  Boyden  was  soon  followed  in  this  work  by  Mr.  James  B. 
Francis.  In  1849,  however,  Mr.  Francis  built  a  radial  inward- 
flow  or  vortex  turbine  for  the  Booth  Cotton  Mills,  Lowell,  Mass.1 
This  turbine,  which  worked  under  a  head  of  19  ft.,  and  when 
tested  showed  an  efficiency  of  79.7%,  or  practically  80%,  may 
be  regarded  as  the  prototype  of  all  American  turbines. 

The  number  of  revolutions  varies  as  the  square  root  of  the 
heads  employed  and  for  the  same  head  the  revolutions  of  different 
turbines  are  inversely  proportional  to  their  diameters.  As  all 
the  early  turbines  were  used  with  low  heads,  about  20  ft.  or  less, 
and  as  already  then,  as  now,  the  tendency  was  to  increase  the 
speed  of  shafting  and  machinery,  builders  naturally  reduced  the 
turbine  diameter. 

Mr.  Francis's  turbine  was  of  the  plain  inward-flow  type,  with 

1  Wood.     Turbines,  p.  89. 

17 


18  MODERN  TURBINE  PRACTICE. 

sufficient  room  in  its  interior  for  the  water  to  turn  and  escape 
axially.  With  the  continued  reduction  of  the  turbine  diameter, 
this  interior  space  became  more  and  more  reduced,  so  that  it 
soon  became  necessary  to  turn  the  water  into  an  axial  direction 
while  still  in  the  runner-bucket,  or,  in  other  words,  to  curve  the 
bucket  from. a  radial  to  a  more  or  less  axial  direction.  This  has 
been  going  on  gradually,  as  can  be  seen  by  comparing  the  early 
forms  of  the  Humphrey  and  the  Swain  turbines  with  the  present 
form  of  the  Hercules,  New  American,  Victor,  Leffel,  and  other 
turbines,  which  have  scarcely  more  interior  space  than  is  required 
to  pass  the  shaft  through  and  have  a  much  greater  part  of  the 
runner-buckets  in  the  axial-  or  parallel-flow  direction  than  in 
the  radial-flow  direction,  while  the  runner-buckets  have  assumed 
such  an  intricate  shape  that  it  is  very  difficult  to  analyze  the 
action  of  the  water  while  flowing  through  these  buckets,  or  to 
mathematically  predetermine  their  shape  for  given  conditions. 

Another  consequence  of  the  reduction  of  the  diameter  is  that 
the  inner  ends  of  the  buckets,  which  closely  approach  the  center 
of  the  turbine,  are  located  on  a  very  small  circle,  which  limits 
their  number  and  gives  them  a  very  close  spacing,  while  the  spacing 
on  the  outer  circumference  becomes  so  large,  6  ins.  and  even 
12  ins.  being  not  uncommon,  that  the  buckets  are  unable  to  properly 
guide  the  water  as  the  best  efficiency  would  demand.  The  area 
through  which  the  water  enters  the  runner,  being  the  outer  cir- 
cumference of  the  runner  multiplied  by  the  axial  dimension  of 
the  bucket  entrance,  decreases,  of  course,  with  the  diameter  of 
the  runner,  and  with  it  and  in  the  same  ratio  decreases  the 
quantity  of  water  passed  through  and  the  power  developed  by  the 
turbine. 

To  prevent  this  decrease  in  entrance  area  and  power,  builders 
have  gradually  increased  the  axial  dimension  of  the  bucket  entrance. 
Thus  the  efforts  made  towards  greater  speed  and  power  have 
transformed  the  plain  inward-flow  turbine-runner  of  fifty  years 
ago  into  the  shape  now  generally  employed. 

The  guide-buckets  have  not  altered  so  much  as  the  runner- 
buckets,  and  of  the  great  variety  of  gate  arrangements  that  have 
been  tried  only  the  following  three  have  come  into  general  use: 

1.  The  cylinder  gate,  moving  in  an  axial  direction,  as  used 


TURBINE  PRACTICE  IN  AMERICA.  19 

by  Mr.  Francis  with  his  early  turbines,  is  now  by  far  the  most 
extensively  employed  gate. 

2.  The  register  gate,  a  rotating  cylinder,  having  slots  which 
correspond  with  the  outlet  openings  of  the  guide-buckets.    This 
gate  is  not  so  much  used  now  as  some  years  ago. 

3.  The  wicket  gate,  having  the  guide-buckets  formed  by  swing- 
ing or  otherwise  movable  blades  or  vanes.    This  gate  is  made 
in  different  forms  and  is  next  to  the  cylinder  gate,  the  most  widely 
used  arrangement. 

Present  Turbine  Practice  in  America.  The  Turbine  as  a 
Hydraulic  Motor. — For  low  heads,  say  up  to  about  40  ft.,  the 
American  type  of  turbine  has  the  great  advantage  over  all  other 
turbine  types  in  common  use,  that  it  gives  the  greatest  number 
of  revolutions  for  a  given  head  and  power  developed,  or  the  great- 
est power  for  a  given  head  and  diameter  of  runner,  while  the 
American  system  of  manufacturing  only  one  line  of  turbines  from 
stock  patterns  has  the  great  advantage  of  enabling  the  builders 
to  fill  orders  cheaply  and  quickly. 

As  already  stated,  the  American  turbine  has  been  developed 
solely  by  experiment,  and  the  testing-flume  at  Lowell,  and  later 
on  that  at  Holyoke,  Mass.,  may  be  called  the  cradle  of  the  Ameri- 
can turbine.  However,  the  greatest  head  available  at  both  these 
flumes  was  but  18  ft.,  and  the  turbines  have  therefore  been  adapted 
and  perfected  for  such  low  heads  only,  while  the  builders  are 
almost  wholly  in  the  dark  in  regard  to  the  action  of  their  tur- 
bines when  used  with  medium  or  high  heads. 

This  absence  of  experience  seems  to  have  been  the  principal 
reason  why  some  of  the  earlier  developments  utilize  the  avail- 
able head  in  several  stages;  for  example,  a  large  power  in  one  of 
the  Eastern  States,  where  a  head  of  80  ft.  is  utilized  in  two  stages 
of  about  40  ft.  each. 

So  far  as  the  writer  is  aware,  results  of  reliable  tests  of  Ameri- 
can turbines,  working  under  heads  much  greater  than  40  ft.,  have 
never  been  published;  and  where  such  tests  have  been  made, 
the  results  have  been  carefully  kept  from  the  public.  It  appears, 
nevertheless,  that  a  number  of  similar  American  turbines  of 
large  power  and  working  at  Niagara  Falls,  N.  Y.,  under  a  head 
of  over  200  ft.  are  giving  a  maximum  efficiency  of  some  68%, 


20  MODERN   TURBINE  PRACTICE. 

while  the  turbines  designed  in  Europe  and  working  at  the  Niagara 
Falls  Power  Company's  plant  are  said  to  give  80%  efficiency.1 

At  another  well-known  power-plant,  utilizing  a  head  of  about 
200  ft.,  the  first  installation  of  American  turbines  gave  an  effi- 
ciency of  a  little  over  40%;  the  second  installation,  also  of  Ameri- 
can turbines,  but  from  another  maker,  gave  an  efficiency  of  a 
little  over  60%;  while  the  third  installation,  which  consisted  of 
turbines  built  in  America,  but  according  to  European  designs, 
gave  an  efficiency  of  nearly  80%. 

The  low  efficiency  of  the  American  turbine,  when  used  under 
high  heads,  is  only  what  is  to  be  expected,  as  runner  and  guide- 
buckets,  constructed  to  give  an  efficiency  of  over  80%  under 
a  head  of  less  than  18  ft.,  cannot  possibly  also  give  a  high  effi- 
ciency under  high  heads,  such  as  200  ft.  or  even  100  ft.  At  the 
same  time,  high  heads  in  most  cases  have  only  a  limited  flow  of 
water,  thus  demanding  a  higher  efficiency  for  the  turbines  employed 
for  their  utilization  than  low  heads,  where  the  flow  is,  as  a  rule, 
more  abundant.  In  general  it  must  be  said  that  the  high  power 
and  speed  of  the  American  turbines  and  the  custom  of  filling  all 
orders  from  stock  patterns  is  also  against  their  use  in  connection 
with  high  heads,  as  may  be  shown  by  two  examples,  as  follows: 

While  making  the  specifications  for  some  double  turbines, 
each  pair  to  develop  5500  H.P.  under  130  ft.  head,  and  at  a  speed 
of  250  revolutions  per  minute,  the  writer,  in  speaking  to  a  well- 
known  turbine  builder  of  the  Central  States  in  regard  to  the 
matter,  found  the  builder  quite  willing  to  bid  for  and  to  supply 
these  turbines  from  his  stock  patterns.  Now,  this  builder's  cata- 
logue shows  that  a  pair  of  turbines  to  develop  5500  H.P.  under 
130  ft.  head  woulol  make  413  revolutions  instead  of  250,  as  required, 
or  that  a  pair  of  turbines  working  under  130  ft.  head  and  running 
at  250  revolutions  per  minute  would  develop  17,312  H.P.  The 
plant  was  subsequently  equipped  with  turbines  of  the  European 
type. 

A  case  showing  still  more  forcibly  how  little   the  American 

1  A.  van  Muyden.  Les  turbines  Fasch  &  Piccard  a  Niagara  Falls.  Ex- 
pediences de  reception.  Bull,  de  la  Soc.  Vaudoise  des  Ing.  et  Arch.,  1895, 
JNo.  8. 


TURBINE  PRACTICE  IN  AMERICA.  21 

turbine  is  adapted  to  high  heads  is  that  of  the  turbines  recently 
installed  by  the  Cataract  Power  Co.,  of  Hamilton,  Ont.,  and  shown 
in  Figs.  30  and  31.  These  are  single  turbines,  designed  and  built 
in  Europe,  developing  each  3000  H.P.  under  256  ft.  head,  and 
at  a  speed  of  286  revolutions  per  minute,  and  give  an  efficiency 
of  80%.  No  doubt  many  American  turbine  builders  would  have 
been  willing  to  supply  the  turbines  for  this  plant  from  their  stock 
patterns,  using,  of  course,  a  pair  of  turbines,  as  otherwise,  under 
this  high  head,  the  end  thrust  would  be  too  great  to  be  properly 
taken  care  of.  Using  the  figures  given  in  a  catalogue  of  McCor- 
mick  turbines,  calculations  show  that  a  pair  of  turbines,  to  develop 
3000  H.P.  under  256  ft.  head,  would  have  a  speed  of  1276  revo- 
lutions per  minute,  instead  of  286,  as  required,  or  that  a  pair  of 
turbines  working  under  256  ft.  head  and  running  at  286  revo- 
lutions would  develop  91,565  H.P.,  or  over  30  times  the  desired 
amount,  and  requiring  a  case  17  ft.  in  diameter  and  over  26  ft. 
long,  while  the  total  floor  space  occupied  by  the  European  tur- 
bines, up  to  center  of  dynamo  coupling,  is  only  11X14J  ft. 

Evidently  the  American  type  of  turbines  is  not  adapted  to 
such  high  heads,  yet  the  head  is  not  high  enough  to  use  impulse 
turbines  to  advantage,  as  may  be  seen  from  the  following  figures, 
taking  the  speed  at  the  bucket  circle  as  v=QA5\/2gH,  which  is 
the  usual  practice.  To  develop  3000  H.P.  under  256  ft.  head 
and  at  a  speed  of  286  revolutions  would  require  seven  impulse 
turbines,  each  having  3  ft.  10J  ins.  diameter  of  bucket  circle  and 
three  3-in.  nozzles,  or  21  nozzles  in  all.  This  would  certainly 
be  a  very  complicated  arrangement,  especially  in  regard  to  the 
regulation  of  so  many  nozzles. 

It  may  here  be  stated  that  the  catalogs  of  builders  of  impulse 
turbines  usually  give  the  over-all  diameter,  that  is,  from  outside 
of  buckets,  instead  of  the  diameter  of  bucket  circle,  which  latter 
is  by  far  the  more  important. 

When  supplying  American  turbines  for  high  heads,  most 
builders  reduce  the  power  of  the  turbines  by  using  smaller  tur- 
bines than  required  for  the  desired  number  of  revolutions  and 
then  draw  the  speed  down  to  the  proper  number  by  means  of 
the  governor  and  the  gates.  If  the  power  of  a  turbine  is  very 
much  in  excess  of  the  required  amount,  turbine  builders  often 


22  MODERN  TURBINE  PRACTICE. 

also  reduce  the  axial  dimension  of  the  runner-bucket  entrance, 
which,  of  course,  affects  the  efficiency  of  the  turbine  in  nearly 
the  same  way  as  would  an  equal  reduction  in  gate-opening,  since 
only  the  entrance  area  is  changed,  while  the  rest  of  the  runner- 
bucket  remains  as  before. 

The  use  of  the  American  turbine  in  connection  with  high 
heads  or  where  special  conditions  have  to  be  met  can  thus  only 
be  regarded  as  a  makeshift,  and  turbines  of  the  European  type 
will  be  preferred  in  all  cases  where  time  and  money  required  for 
their  installation  are  available,  as  is  shown  by  the  plants  of  the 
Niagara  Falls  Power  Co.  and  the  East  Jersey  Water  Co.,  in  the 
United  States,  and  the  Cataract  Power  Co.,  already  referred  to, 
the  Shawinigan  Water  &  Power  Co.,  and  the  plant  at  Montmorency 
Falls,  in  Canada.  It  is  a  matter  for  wonder  that  American  tur- 
bine manufacturerrs  will  not  supply  turbines  of  the  European 
type,  where  the  conditions  make  their  use  advisable;  but  the 
writer  found  it  practically  impossible  to  induce  builders  to  bid 
on  anything  else  except  the  American  standard  type,  even  when 
they  were  furnished  with  complete  drawings  and  relieved  of  all 
responsibility  in  regard  to  the  performance  of  the  design.  Of 
course,  the  writer  is  aware  that  some  manufacturers  make  a  special 
high-pressure  turbine,  but  except  those  built  by  one  firm  these 
machines  need  not  to  be  considered  here,  as  the  guides  and  runners 
are  the  same  as  those  of  the  regular  American  turbine,  the  only 
difference  being  in  the  general  arrangement. 

But  apart  from  the  fact  that  the  American  type  of  turbine 
is  not  suitable  for  high  heads,  the  shape  of  the  runner  as  now 
generally  used  has  some  features  which  violate  the  rules  to  be 
observed  for  obtaining  a  high  efficiency.  In  Fig.  8  is  shown  a 
drawing  of  a  vane  and  in  Fig.  9  a  section  through  one  half  of  the 
runner  and  guide  of  an  American  type  of  turbine  as  built  in  France,1 
by  reference  to  which  the  following  will  be  more  readily  under- 
stood. 

The  water  enters  the  runner-buckets  in  a  radial  inward  direc- 
tion, is  sharply  turned  into  an  axial  direction,  and  leaves  the 


1  The  writer  was  unable  to  get    satisfactory  material  for  these  figures 
from  American  builders. 


TURBINE  PRACTICE  IN  AMERICA. 


23 


24  MODERN  TURBINE  PRACTICE. 

buckets,  after  another  turn,  in  a  direction  slanting  between  axial 
and  radial  outward,  the  latter  direction,  being  partly  due  to  the 
centrifugal  force.  It  will  at  once  be  obvious  that  the  two  changes 
in  direction  cause  a  loss  of  head,  also  that  the  great  length  of 
the  buckets  means  a  great  frictional  resistance  or  another  loss  of 
head.  As  has  already  been  pointed  out,  the  buckets  very  closely 
approach  the  shaft,  thus  necessitating  a  close  spacing  of  the  vanes 
at  their  inner  and  a  very  wide  spacing  at  their  outer  end,  too  wide 
a  spacing,  in  fact,  to  properly  guide  the  water.  However,  the 
cause  for  the  greatest  loss  in  a  vortex  turbine  is  that  the  ter- 
minal edge  of  the  vane,  being  approximately  radial,  has  a  speed 
at  its  inner  end  widely  different  from  that  at  its  outer  end,  but 
for  best  efficiency  the  speed  of  the  terminal  edge  should  be  the 
same  as  the  relative  speed  of  the  water  at  exit  from  the  runner- 
buckets  multiplied  by  the  cosine  of  the  angle  of  the  relative  direc- 
tion of  the  water  or  vt  =  ct-  cosine  f.  This  relation  of  speeds  can 
therefore  exist  only  at  one  point  along  the  terminal  edge  of  the 
vane;  at  all  other  points  there  will  be  a  loss  of  head,  increasing 
with  the  distance  from  the  point  of  correct  speed.  This  loss 
is  in  the  form  of  velocity-head  inside  of  and  up  to  the  point  of 
correct  speed,  and  from  that  point  outward  the  loss  is  due  to  the 
fact  that  the  runner-vane  is  moving  out  of  the  way  of  the  water 
before  having  completely  accomplished  its  object  in  turning  or 
deflecting  the  water  into  the  proper  direction  for  discharge. 
Owing  to  the  fact  that  the  water  leaves  the  runner-buckets  in 
a  direction  slanting  between  axial  and  radial  outward,  the  draft- 
tube  or  the  draft-elbow  or  tee  has  to  be  much  larger  in  diameter 
at  the  point  of  the  runner  discharge  than  the  runner  itself,  as 
otherwise  the  water  would  strike  the  walls  of  the  tube  and  be 
forced  to  turn  too  quickly.  However,  the  remedy  of  increasing 
the  diameter  introduces  another  evil.  According  to  the  catalogs 
of  turbine  builders,  the  draft-tube  at  the  point  of  the  runner 
discharge  has  an  area  about  twice  as  large,  more  or  less,  as  the 
area  corresponding  to  the  diameter  of  the  runner;  in  other  words, 
the  water  issuing  from  the  runner  has  its  speed  abruptly  reduced 
to  one  half,  and  this  sudden  conversion  and  shock  of  course  causes 
loss  of  head. 

American  manufacturers  have  increased  the  speed  and  power 


TURBINE  PRACTICE  IN  AMERICA.  25 

of  their  turbines  to  the  utmost  practical  limit,  and  it  is  safe  to 
predict  that  any  further  increase  of  speed  and  any  further  crowd- 
ing of  power  into  a  turbine  of  given  diameter  will  result  in  a 
decided  decrease  in  efficiency.  French  builders  of  the  American 
type  of  turbines,  unlike  the  American  builders,  which  use  the 
same  pattern  for  all  heads,  have  different  patterns  to  suit  different 
heads,  as  has  been  stated  already,  and  they  also  have  not  increased 
the  speed  and  power  of  their  turbines  to  the  extent  to  which 
American  builders  have  done.  The  following  figures,  which  are, 
for  the  American  make,  taken  from  the  latest  catalog  of  one  of 
the  best-known  turbine  manufacturers,  and,  for  the  French  make, 
taken  from  material  obtained  at  the  Paris  Exhibition  in  1900, 
will  show  this  difference.1 

Diameter  of  runner  at  initial  or  entrance  rim: 


American  practice:  D  =1.57  to  1 


•63s|: 


French  practice:        D=  1.9  to  2.1 


Ratio  of  axial  dimension  of  runner-bucket  entrance  W  to 
diameter  of  runner  at  initial  or  entrance  rim: 

American  practice:  W:D=1:2  to  1:2.12. 
French  practice  :      W  :  D  =  1  :  2.26  to  1  :  2.34. 

Velocity  of  runner  at  initial  or  entrance  rim: 

American  practice:  v=  0.705  to  Q.77V2gH. 
French  practice  :       v  =  0.68  to  0.75  V2gH. 

The  majority  of  the  American  turbines  are  now  regulated  by 
cylinder  gates,  as  they  are  not  only  simple  but  also  cheap,  and 
the  latter  appears  to  be  the  main  consideration.  It  has  already 
been  pointed  out  that  cylinder  gates  do  not  give  good  efficiencies 
with  part  loads,  except  when  additional  crowns  are  used.  This, 


iz.  Bauz.,  Feb.  9,  1901,  p.  53;    also   Zeitsch.  d.  V.  deutsch.  Ing., 
Dec.  28,  1901,  p.  1842. 


26  MODERN  TURBINE  PRACTICE. 

however,  is  not  possible  with  the  American  type  of  runner,  owing 
to  the  complicated  shape  of  the  buckets.  A  number  of  manu- 
facturers therefore  cast  on  to  the  face  of  tlie  runner-vanes,  near 
the  entrance  edge,  projections  which  in  shape  somewhat  resemble 
a  half  of  a  lens.  These  projections  are  shown  in  Fig.  9,  and  are 
intended  to  prevent  the  water  from  turning  too  abruptly,  but 
are  also  expected  to  act,  to  a  limited  extent,  in  the  same  way  as 
additional  crowns. 

With  full  gate-opening,  the  American  type  of  turbine  is  a 
vortex  turbine,  working  with  a  great  amount  of  reaction,  but 
this  changes  as  the  gate  is  closing,  and  with  very  small  gate-open- 
ings the  water  flows  radially  inward  and  issues  from  the  runner- 
buckets  along  the  edge  near  and  parallel  to  the  shaft  and  the 
turbine  works  without  any  reaction,  but  with  action  only.  As 
the  reaction  is  decreased,  the  initial  angle  of  the  runner-bucket, 
(t,  should,  for  best  efficiency,  also  decrease,  and  one  American  tur- 
bine-builder has  therefore  divided  the  axial  lengths  of  the  vane 
at  the  bucket  entrance  into  three  parts,  each  having  a  different 
initial  angle.  These  angles  do  not  change  gradually,  but  by 
abrupt  steps,  which,  however,  steadily  diminish  in  width  and 
disappear  entirely  some  distance  in  from  the  entrance.  That 
part  of  the  bucket  entrance  which  is  the  last  to  be  covered  by 
the  closing  of  the  gate  has,  of  course,  the  smallest  initial  angle, 
as  it  is  here  where  the  reaction  ceases  and  action  only  is  at  work. 
The  steps  or  shelves  formed  by  the  changes  of  angles  have  to  a 
small  degree  the  effect  of  the  lens-shaped  projections  mentioned 
above. 

It  seems  that  the  hydraulic  efficiency  of  most  American  vortex 
turbines  would  be  increased  by  running  them  at  lower  speed 
than  they  are  listed  in  the  catalogs.  This  was  clearly  shown 
by  some  experiments  made  recently  by  a  German  turbine -builder 
to  ascertain  the  merits  of  different  types  of  inflow  reaction  tur- 
bines when  working  under  low  heads.1  One  of  the  turbines 
tested  was  a  30-in.  vortex  turbine  built  by  a  well-known  Ameri- 
can manufacturer,  and  which,  under  a  head  of  7  ft.,  should  run, 
according  to  the  catalog,  at  143  revolutions  per  minute  and  give 

1  Zeitsch.  d.  V.  deutsch.  Ing.,  June  13,  1903,  p.  841. 


TURBINE  PRACTICE  IN  AMERICA.  27 

an  efficiency  of  80%  with  full  gate.  The  actual  efficiency  at 
143  revolutions  was  64%  with  full  gate-  and  63%  with  0.75  gate- 
opening.  This  turbine  gave  the  best  efficiency  when  running  at 
124  revolutions,  viz.,  63.5%  with  full  gate-  and  72.5%  with  0.75 
gate-opening;  thus  by  reducing  the  speed  by  13.3%  the  maxi- 
mum efficiency  was  increased  by  8.5%. 

From  theoretical  considerations  it  also  appears  that  the  effi- 
ciency of  the  American  vortex  turbine,  both  at  full  and  part 
gate-opening,  would  be  increased  by  leaving  off  the  scoop-shaped 
discharge  end  of  the  runner-vanes,  giving  this  end  a  form  similar 
to  the  one  shown  hi  Fig.  25  or  26,  and  having  a  different  angle 
of  relative  discharge,  denoted  by  f  in  Fig.  10,  at  different  dis- 
tances from  the  centre  of  the  runner,  so  that  the  equation 

cosine  r=—  will  be  at  least  approximately  satisfied  at  every  point 

along  the  discharge  edge  of  the  runner-vanes.  This  would  not  only 
allow  the  shape  of  the  runner-buckets  to  be  more  readily  analyzed, 
but  it  would  also  decrease  the  length  of  the  path  of  the  water  in 
the  runner-buckets  and  with  it  decrease  the  friction  loss.  It 
would  also  permit  to  have  the  entrance  area  of  the  draft-tube  of 
the  same  size  as  the  discharge  area  of  the  runner  and  the  water 
issuing  from  the  runner-buckets  would  have  both  the  direction 
and  speed  consistent  with  the  requirements  for  best  efficiency 
and  agreeing  with  the  theory  of  turbines. 

German  builders  of  turbines  have  greatly  improved  the  effi- 
ciency of  the  American  vortex  turbine  by  properly  designing  the 
runner-buckets  and  giving  them  a  shape  as  indicated  in  Fig.  22. 

Present  Turbine  Practice  in  America.  The  Turbine  as  a 
Machine. — So  far  the  American  turbine  has  only  been  considered 
as  a  hydraulic  motor,  but  it  may  be  well  to  consider  it  also  as  a 
machine. 

Turbines  have  not  yet  come  to  be  regarded  as  important 
machines,  and  builders  therefore  employ  in  their  construction 
such  materials  and  workmanship  as  are  only  used  for  second-  and 
third-class  machinery,  in  sharp  contrast  to  European  practice, 
where  turbines  are  constructed  with  the  same  care  as  high-class 
steam-engines. 

For  installations  with  vertical  turbines,  the  builders,  besides 


CIVIL  BQNI 


28  MODERN  TURBINE  PRACTICE. 

furnishing  the  turbine  proper,  can  only  prepare  plans  and  give 
advice  in  regard  to  the  general  arrangement,  while  the  choice  of 
material  and  workmanship  rests  with  the  purchaser  of  the  tur- 
bine. One  sees,  therefore,  a  great  variety  of  settings,  from  the 
crazy  wooden  flume  stuck  to  the  outside  of  a  dilapidated  mill 
to  the  modern  concrete  and  steel  construction. 

The  use  of  turbines  on  horizontal  shaft,  made  possible  by 
the  use  of  the  draft-tube,  has  been  rapidly  increasing  during 
recent  years,  and  while  this  arrangement  means  a  very  great 
advance  in  general,  practically  no  improvements  have  been  made 
in  the  constructive  details  of  horizontal  turbines. 

The  case  for  such  turbines  consists  usually  of  cast-iron  heads 
and  a  shell  made  of  low  quality  steel  plate,  barely  thick  enough 
to  withstand  the  interior  water-pressure  and  having  two  light 
steel  I  beams  fastened  along  its  bottom,  supposed  to  stiffen  the 
whole.  The  turbines  themselves  and  such  main  bearings  and 
gate  shaft  bearings  as  are  located  inside  of  this  case  are  held 
in  place  and  fastened  to  or  braced  against  the  thin  shell  plate 
by  cast-iron  or  gas-pipe  supports.  The  regulating-gate  rigging 
and  other  parts  are  often  bolted  or  riveted  to  the  outside  of  the 
shell,  while  the  outside  main  bearings  are  either  carried  on  little 
shelves  cast  onto  the  heads  of  the  case  or  are  bolted  to  the  draft- 
tube  elbow  or  elbows,  or  supported  by  yokes  resting  on  the  above- 
mentioned  I  beams. 

It  is  only  reasonable  to  assume,  especially  when  it  is  con- 
sidered that  the  rivet-  and  bolt-holes  in  the  plates  forming  the 
case  are  often  badly  matched,  and  the  drift-pin  is  freely  used 
during  erection,  that  the  water-pressure  in  the  case  due  to  the 
head  under  which  the  turbine  is  working  will  somewhat  alter 
the  shape  of  the  case  from  what  it  is  while  the  case  is  empty,  in 
which  state,  of  course,  all  assembling,  riveting,  bolting,  and  adjust- 
ing was  done,  and  this  alteration  of  shape  must  naturally  throw 
everything  that  is  fastened  to  the  case  out  of  alinement,  besides 
setting  up  stresses  not  provided  for  hi  the  design. 

The  incessant  surging  or  oscillating  of  the  water  in  the 
penstock  and  in  the  draft-tube,  due  principally  to  changes  in  the 
gate-opening  in  regulating  the  turbine,  causes  the  water-pressure 
u*  the  case  to  alternately  rise  above  and  sink  below  the  normal 


TURBINE  PRACTICE  IN  AMERICA.  29 

pressure  due  to  the  working-head.  These  variations  are  greatest 
where  long  penstocks  and  draft-tubes  are  used,  and  they  keep 
the  case  and  everything  fastened  to  it  continually  working  or 
moving  and  under  constantly  varying  stresses,  a  state  of  affairs 
certainly  not  productive  of  easy  running  QT  long  life  of  the  turbine. 

It  may  be  mentioned  here  that  the  surging  and  with  it  the 
rise  and  fall  of  the  pressure  in  the  turbine-case  may  even  take 
place  with  a  steady  load  on  the  turbine  and  a  constant  gate-open- 
ing. In  such  cases  this  surging  will  usually  be  found  to  be  due 
to  wave  motion  and  eddies  at  the  penstock  entrance  if  the  pen- 
stock is  short,  or  to  eddies  in  the  penstock  itself  if  the  latter  is 
long  and  not  properly  designed. 

When  obliged  to  employ  steel-plate  cases,  the  writer  has 
mitigated  this  evil  somewhat  by  using  thicker  plates  and  deeper 
I  beams  than  were  proposed  by  the  builders. 

Another  fault  of  steel-plate  cases  is  the  difficulty  of  properly 
shaping  them,  and  in  consequence  the  water  while  passing  through 
such  cases  is  subjected  to  abrupt  changes  in  direction  and  speed, 
and  to  reduce  the  loss  in  working-head  caused  by  such  changes 
the  cases  are  made  larger  than  would  be  required  if  easy  water- 
ways could  be  obtained. 

A  great  number  of  plants  have  been  installed  with  two  or 
more  turbines  in  one  case  and  admitting  the  water  through  the 
end  of  the  case.  If  local  conditions  make  it  necessary  that  the 
water  shall  flow  towards  the  turbine  in  an  axial  direction,  the 
open  turbine-chamber  would  be  much  the  better  arrangement; 
but  where  circumstances,  such  as  high  heads,  cost,  etc.,  demand 
the  employment  of  a  case,  the  latter  should  be  considerably  larger 
in  diameter  than  the  diameter  of  the  turbines  would  otherwise 
require,  so  as  to  have  sufficient  area  for  the  axial  flow  of  the  water 
to  reach  the  second  and  any  further  turbines  that  may  be  in 
the  case  without  unnecessary  loss  of  head. 

Below  the  turbines  the  axial  flow  of  the  water  is  completely 
blocked  by  the  draft  tube  or  tubes,  and  this  part  of  the  cross- 
sectional  area  of  the  case  is  therefore  lost.  By  setting  the  tur- 
bine shaft  below  the  centre  line  of  the  case,  this  lost  area  is  reduced 
and  the  useful  area  above  the  turbines  increased,  so  that  suffi- 
cient area  for  the  axial  flow  of  the  water  may  be  obtained,  with 


30  MODERN  TURBINE  PRACTICE. 

little  or  no  increase  in  diameter  over  that  required  for  a  case  with 
side  inlet. 

To  have  thrust  and  other  bearings,  gate-shafts,  gears,  racks, 
guide-rollers,  set-screws,  and  other  moving  or  adjustable  parts 
inside  the  turbine-case  where  they  cannot  be  inspected  or  adjusted, 
as  is  now  the  universal  custom  with  builders,  must  also  be  con- 
sidered faulty  construction,  the  more  so  as  it  could  be  easily  avoided. 

The  size  of  the  turbine-shaft  as  generally  supplied  by  builders 
.is  barely  sufficient  to  transmit  the  power  generated  by  the  tur- 
bine, whereas  the  shaft  should  be  considerably  stronger  than  the 
power  alone  would  demand,  particularly  for  turbines  on  hori- 
zontal shafts,  and  here  again  a  greater  excess  of  strength  is  required 
for  a  pair  of  turbines  on  one  shaft  than  for  a  single  turbine. 

Weak  and  springy  turbine-shafts  and  bad  workmanship  mean 
large  clearances,  and  these  in  turn  mean  leakage  and  therefore 
loss  of  water  and  reduction  in  turbine  efficiency. 

When  ordering  a  large  turbine  on  a  horizontal  shaft  for  a 
nead  of  40  ft.  or  more  builders  will  usually  advise  the  purchaser 
-co  use  a  pair  of  turbines  on  one  shaft  to  avoid  the  end  thrust, 
while  for  heads  of  80  ft.  or  more  most  builders  will  decline  to 
assume  any  responsibility  in  regard  to  the  thrust-bearing  if  a 
single  turbine  is  used,  claiming  that  no  such  bearing  can  be  made 
that  will  properly  take  care  of  the  end  thrust  of  large  single  tur- 
bines under  high  heads.  This  is  of  course  a  preposterous  asser- 
tion in  the  view  of  the  daily  experience  of  thousands  of  ocean 
steamers,  where  the  whole  propelling  power  is  converted  into 
end  thrust  and  15,000  H.P.  and  more  are  applied  to  a  single 
shaft.  It  must  be  said,  however,  that  thrust-bearings  to  work 
satisfactorily  must  be  well  designed,  of  good  material  and  liberal 
proportions,  and  of  superior  workmanship. 

However,  the  American  type  of  turbine  when  considered  as  a 
machine  also  has  its  advantages,  the  foremost  of  which  are  that 
the  turbine  is  simple,  has  but  few  parts,  and  is  easily  taken  apart 
and  assembled. 

Causes  of  Lack  of  Progress  among  American  Turbine- 
builders. — The  backward  state  of  the  art  and  the  scarcity  of 
improvements  in  American  turbine  construction  is  certainly  sur- 
prising when  compared  with  the  advanced  state  to  which  nearly 


TURBINE  PRACTICE   IN  AMERICA.  31 

every  other  line  of  machinery  has  been  brought  in  America.  There 
is  this  to  be  said  for  the  turbine-builder,  however — that  he  would 
have  very  little  sale  for  a  high-class  turbine.  The  fault  rests 
chiefly  with  the  purchaser,  who  generally  believes  that  water- 
power  costs  little  or  nothing,  and  that  any  turbine  which  will 
turn  his  machinery  is  good  enough. 

It  is  also  very  much  to  be  regretted  that  the  practice  of  test- 
ing turbines  in  the  flume  at  Holyoke  has  become  so  universal,  as 
although  these  tests  may  give  very  accurate  figures,  showing 
how  the  efficiencies  of  different  sizes  and  makes  of  turbines  com- 
pare with  each  other  when  tested  with  a  head  of  less  than  18  ft., 
and  under  the  most  favorable  conditions,  they  do  not  give  any 
information  whatever  about  the  real  or  absolute  efficiency  the 
turbine  will  show  when  properly  set  up  and  connected  in  its 
intended  place  and  working  under  a  head  perhaps  five  or  ten 
times  greater  than  that  available  at  Holyoke. 

The  Holyoke  tests,  as  usually  made,  with  the  turbine  set  ver- 
tical in  an  open  turbine-chamber,  will  show  an  efficiency  closely 
approaching  the  hydraulic  efficiency  of  the  turbine,  but  the  same 
turbine  that  has  shown  at  Holyoke  an  efficiency  of,  say,  82% 
under  a  17-ft.  head,  when  installed  in  its  intended  place,  mounted 
on  a  horizontal  shaft  and  enclosed  in  a  case,  may  easily  give  an 
efficiency  ten  or  more  per  cent  less  than  shown  at  Holyoke, 
although  the  head  used  might  be  the  same  in  both  cases.  This 
difference  may  be  due  to  increased  friction  in  the  bearings,  faulty 
design  of  the  case  and  draft-tube,  poor  workmanship,  bad  aline- 
ment,  etc.,  and  it  is  little  consolation  to  the  owner  that  the  tur- 
bine has  given  good  results  at  Holyoke. 

To  test  turbines  in  their  place  and  under  working  conditions, 
as  is  nearly  always  done  in  Europe,  would  in  most  cases  cost  but 
little  more  than  the  Holyoke  test,  but  the  results  would  be 
immensely  more  valuable  to  the  purchaser,  to  the  builder  of  the 
turbines,  and  to  the  engineering  profession  generally,  provided, 
of  course,  the  tests  are  made  by  competent  persons. 

Two  cases  may  be  mentioned  to  show  the  slight  value  of  the 
Holyoke  test.  A  year  ago  the  writer  made  a  contract  for 
some  1400-H.P.  turbines  to  work  under  a  head  of  110  ft.,  and 
a  well-known  builder  offered  to  guarantee  80%  efficiency.  Upon 


32  MODERN  TURBINE  PRACTICE. 

being  informed  that  the  tests  were  to  be  made  with  the  turbines 
in  place,  he  modified  his  guarantee  to  80%  at  Holyoke  and  73% 
in  place.  The  other  case  is  that  of  a  large  power  plant  in  Canada, 
containing  when  fully  equipped  72  turbines  of  200  H.P.  each, 
working  under  a  head  of  11  ft.  The  builder  guaranteed  the  cus- 
tomary 80%  efficiency,  shipped  one  of  the  turbines  to  Holyoke, 
and  was  able  to  show  test  results  of  about  83%.  The  engineers 
in  charge  of  the  construction  of  the  plant  in  question  took  at 
random  a  turbine  from  the  lot  received  and  had  it  tested  at  Holyoke, 
but  the  efficiency  was  only  72%,  and  it  required  a"  great  deal 
of  polishing  and  improving  to  bring  the  efficiency  of  this  turbine 
up  to  80%,  and  the  conclusion  is  naturally  that  only  the  two 
turbines  tested  are  up  to  the  guaranteed  80%,  and  all  the  rest 
have  an  efficiency  of  about  72%. 

The  results  of  efficiency  tests  made  at  Holyoke  cannot  be 
directly  compared  with  the  results  obtained  by  tests  made  in 
Europe,  as  has  been  shown  repeatedly  by  having  turbines  tested 
at  Holyoke  and  retested  in  Europe,  the  latter  test  invariably 
giving  a  much  lower  efficiency  than  the  Holyoke  tests. 

It  is  not  the  writer's  intention  to  discuss  here  the  intricate 
questions  involved  in  the  testing  of  turbines,  nor  to  say  which 
•of  the  test  results  are  nearest  to  the  actual  efficiency ;  but  it  may 
fae  stated  here  that  European  engineers  maintain  this  difference 
to  be  principally  due  to  the  different  methods  of  water  measure- 
ment. 

As  an  example  may  be  mentioned  a  16-in.  turbine  bought 
by  a  European  builder  from  one  of  the  largest  and  best-known 
turbine  manufacturers  in  the  United  States,  the  object  being  to 
take  up  the  construction  of  American  turbines  if  the  high  effi- 
ciencies claimed  could  be  verified.  The  turbine  was  duly  tested 
at  Holyoke  in  the  spring  of  1900  and  retested  in  Germany  in  the 
spring  of  1901.  The  tests  in  Germany  were  made  by  one  of  the 
highest  authorities  on  turbines,1  and  the  testing  flume  was  equipped 
with  the  latest  and  most  refined  instruments. 

The  efficiencies  of  the  American  turbine  shown  at  the  Holyoke 

1  Professor  A.  Pfarr,  of  the  Polytechnicum  in  Darmstadt,  formerly  for 
many  years  chief  engineer  of  the  works  of  J.  M.  Voith,  turbine  manufac- 
turer, Heidenheim,  Germany. 


TURBINE  PRACTICE  IN  AMERICA. 


33 


test  and  at  the  German  test  are  given  below,  and  for  comparison 
the  efficiencies  now  commonly  realized  with  European  reaction 
turbines,  when  tested  in  the  same  manner  as  the  American  tur- 
bine has  been  in  Germany,  are  also  given.1  These  figures  will 
bear  out  the  writer's  statement  that  the  shape  of  the  American 
type  of  runner  is  not  adapted  to  give  the  best  efficiency,  especially 
with  part  gate-opening. 


Discharge                                     .... 

1  0 

0.9 

0.8 

0.7 

0.6 

American  turbine,  Holyoke  test.  . 
American  turbine,  German  test.  .  . 
European  turbine,  German  test.... 

0.81 
0.718 
0.80 

0.795 
0.703 
0.81 

0.765 
0.693 
0.82 

0.725 
0.658 
0.81 

0.67 
0.591 
0.80 

Discharge                                      •   .  • 

0.5 

0.4 

0.3 

0.2 

American  turbine   Holyoke  test  . 

American  turbine  German  test 

0  491 

0  358 

0  121 

European  turbine  German  test 

0  79 

0  76 

0  70 

0.60 

The  discharge  is  here  the  proportional  amount  actually  dis- 
charged and  should  not  be  confounded  with  gate-opening.  The 
smallest  discharge  tested  at  Holyoke  was  0.6.  The  total  weight 
on  the  turbine  step  was  25%  greater  during  the  Holyoke  tests 
than  during  the  German  tests. 

The  turbine  tests  made  at  the  Centennial  Exhibition  in  Phila- 
delphia, 1876,  have  never  been  given  much  credit  by  either  Ameri- 
can or  European  engineers. 

As  the  term  gate-opening  is  at  present  employed  indiscrim- 
inately for  both  gate-opening  and  discharge,  and  as  many  users 
of  turbines  when  comparing  efficiencies  think  that  with,  say, 
one  half  gate-opening  the  turbine  will  only  pass  one  half  of  the 
amount  of  water  used  with  full  gate,  the  writer  would  here  call 
attention  to  the  great  difference  between  the  two.  For  example, 
the  American  turbine  referred  to  above  discharged  0.6  of  the 
amount  of  water  used  with  full  gate,  with  a  gate-opening  of  only 
0.321 ;  that  is,  the  discharge  was  nearly  twice  as  great  as  the  gate- 
opening. 


1  Zeitsch.  d.  V.  deutsch.  Ing.,  June  7,  1902,  p.  845;  also  a  defence  of  the 
Holyoke  test  by  Mr.  Clemens  Herschel  and  reply  to  same  in  Zeitsch.  d.  V. 
deutsch.  Ing.,  Nov.  22,  1902,  p.  1788. 


34  MODERN  TURBINE  PRACTICE. 

The  importance  of  a  high  efficiency  in  cases  where  water  is 
bought  or  power  sold  may  be  easily  shown.  Supposing  the  water 
required  to  develop  one  gross  or  theoretical  horse-power  costs 
$10.00  per  year,  which  is  about  the  average  of  prices  paid  in  the 
New  England  States,  then  the  net  or  effective  horse-power  costs 
$14.30  with  70%  and  $12.50  with  80%  efficiency  of  turbines, 
or  a  saving  of  $1.80  per  effective  horse-power  in  favor  of  the  tur- 
bine with  the  higher  efficiency.  With  5%  interest  on  capital 
invested  and  10%  for  depreciation,  taxes,  etc.,  or  a  total  of  15%, 
which  is  very  high,  the  above  $1.80  would  pay  the  interest  on 
$12.00,  or,  in  other  words,  the  turbine  giving  80%  efficiency  could 
cost  $12.00  more  per  horse-power,  or  a  1000-H.P.  turbine  could 
cost  $12,000  more,  than  a  turbine  giving  only  70%  efficiency, 
without  increasing  the  cost  per  effective  horse-power  per  year. 
As  a  1000-H.P.  horizontal  double  turbine  of  the  American  type, 
for  80  or  100  ft.  head,  complete  with  case  and  draft-tube  and 
erected  in  place,  costs  about  $6000,  and  will  give  about  70% 
efficiency,  a  properly  designed  and  built  turbine  giving  80% 
could  cost  $18,000  without  being  more  expensive  than  ;the  other; 
but  as  such  a  turbine  could  be  bought  for  about  $10,000,  the  higher- 
priced  turbine  really  means  a  saving  in  capital  invested  to  the 
amount  of  $8000,  or  $8  per  horse-power. 

Or  supposing  that  power  is  sold  at  $15  per  year  for  one  effective 
mechanical  horse-power  at  the  turbine-shaft  and  that  the  water- 
supply  is  limited,  the  amount  of  water  required  to  develop 
one  effective  horse-power  with  70%  efficiency  will  give  1.143  H.P., 
worth  $17.14  per  year,  with  80%  efficiency.  The  difference  of 
$2.14  in  favor  of  the  turbine  with  the  higher  efficiency  is  equal 
to  an  interest  of  15%  as  above,  on  $14.27,  or  a  1000-H.P.  tur- 
bine giving  80%  efficiency  could  cost  $14,267  more  than  a  tur- 
bine giving  70%  without  being  more  expensive. 

Other  causes  that  have  retarded  the  progress  in  turbine  con- 
struction may  be  mentioned,  such  as  the  belief  of  purchasers  that 
the  turbine  is  a  very  simple  machine,  and  that  they  know  all 
about  it,  and  therefore  do  not  need  the  service  of  a  hydraulic 
engineer;  that  the  few  hints  given  in  turbine  catalogs  are  all 
that  is  necessary  to  know,  and  that  any  third-class  machinist 
or  millwright  who  has  once  helped  to  install  a  turbine  is  a  com- 


TURBINE  PRACTICE  IN  AMERICA.  35 

petent  hydraulic  engineer.  That  the  ignorance  of  the  purchasers 
in  regard  to  turbines  is  well  known  to  builders  is  shown  by  the 
unreasonable  claims  and  statements  made  in  turbine  catalogs. 

But  hydraulic-power  engineers,  where  consulted  in  connec- 
tion with  water-power  developments,  are  also  often  to  blame 
for  not  properly  explaining  to  their  clients  the  advantages  of  a 
high-class  turbine,  and  the  turbine  specifications  prepared  by 
engineers  are  as  a  rule  poor,  superficial,  and  insufficient,  and 
no  effort  is  made  to  ascertain  whether  the  specifications  have 
been  complied  with  or  not.  It  may  be  said  that  there  are  many 
so-called  hydraulic  engineers  who  do  not  know  any  more  about 
turbines  than  what  they  can  learn  from  builders'  catalogs,  and 
who  apparently  have  not  the  least  idea  that  anything  better  can 
be  produced  in  the  line  of  turbines  than  is  generally  furnished 
by  the  builders. 

Another  reason  that  turbines  have  advanced  so  little  in  America, 
and  that  their  design  has  not  yet  been  placed  upon  a  scientific 
basis,  is  the  lack  of  attention  paid  to  the  subject  by  the  engineer- 
ing schools  and  the  want  of  an  up-to-date  text-book  on  turbine 
design.  In  all  European  colleges  the  theory  and  the  design  of 
turbines  is  taught  with  the  same  care  as  the  theory  and  the  design 
of  steam-engines,  while  in  many  American  colleges,  it  seems, 
the  theory  of  turbines  is  only  casually  mentioned  hi  the  lectures 
on  the  flow  of  water,  while  turbine  design  is  not  taught  at  all. 

The  hydraulic-power  engineer,  when  called  upon  to  develop 
a  large  water-power,  say  under  200  ft.  head,  finds  himself  in  a 
very  awkward  position.  If  he  chooses  single  turbines,  there 
will  be  trouble  with  the  thrust-bearings. 

If  the  turbines  are  to  drive  dynamos  or  other  direct-connected 
machinery,  and  are  selected  to  give  the  right  speed,  their  power 
will  usually  be  enormously  too  large,  and  if  selected  to  give  the 
right  power,  the  speed  as  a  rule  will  be  much  too  high,  and  special 
dynamos  or  machinery  would  have  to  be  built  to  suit  the  tur- 
bine?, while  the  efficiency  of  the  latter  would  be  low  in  any  case. 
If  he  goes  to  Europe  for  his  turbines,  there  will  be  delays  and  much 
extra  expense. 

For  a  number  of  plants  with  whose  construction  the  writer 
was  connected  the  cost  of  the  turbines  amounted  to  between 


36  MODERN  TURBINE  PRACTICE. 

4  and  10%  of  the  total  cost  of  the  development.  Now,  while 
the  turbine  is  the  most  important  element  in  a  development,  its 
cost  is  comparatively  small  and  the  increased  price  of  a  high-class 
turbine  would  be  hardly  noticeable  in  the  total  cost  of  the  develop- 
ment. Why  then  should  the  hydraulic-power  engineer  be  obliged 
to  design  the  whole  plant  with  only  one  point  in  view,  that  is, 
to  suit  the  standard  turbine  patterns?  And  has  the  time  not 
arrived  yet  when  the  greatly  varying  conditions  of  head,  amount 
of  water,  size  and  speed  of  turbine-units,  etc.,  demand  more  than 
just  one  line  of  patterns  for  the  hydraulic  engineer  to  choose  from? 

The  general  cry  for  cheapness  and  the  striving  to  meet  com- 
petition by  reducing  the  cost  of  production  seems  to  have  done 
more  harm  in  the  manufacture  of  turbines  than  in  most  other 
lines.  Economy  is  one  of  the  principles  on  which  an  industry 
must  be  based  to  successfully  meet  competition,  but  to  lower 
the  quality  of  material  and  workmanship  and  to  reduce  the  hydraulic 
and  mechanical  efficiency  of  turbines  for  mere  cheapness'  sake 
is  certainly  a  wrong  application  of  the  principles  of  economy. 

Thousands  of  dollars  are  often  spent  in  the  general  construc- 
tion work  for  a  development,  to  gain  a  few  additional  feet  of  head, 
where  a  greater  gain  in  power  might  be  obtained  by  expending 
a  couple  of  hundreds  of  dollars  more  on  the  turbine  equipment. 


CHAPTER  III. 
CLASSIFICATION  OF  TURBINES. 

BEFORE  going  into  the  details  of  the  turbine  types  best  adapted 
to  the  different  heads,  it  may  be  well  to  give  here  the  general 
characteristics  and  properties  and  the  advantages  and  disadvan- 
tages of  the  different  classes  of  turbines.  Turbines  are  classified, 
according  to  the  manner  in  which  the  water  performs  its  work 
in  flowing  through  them,  into  reaction  and  action  turbines.  The 
action  turbines  are  again  divided  into  two  sub-classes,  viz.,  action 
turbines  with  free  deviation  and  action  turbines  with  limited 
buckets  or  limit  turbines. 

The  principal  difference  between  reaction  and  action  turbines 
is  in  the  velocity  with  which  the  water  issues  from  the  guide- 
buckets,  or,  what  is  the  same,  in  the  presence  or  absence  of  pres- 
sure at  the  clearance.  The  principles  of  working  of  each  of  the 
different  classes  and  sub-classes  of  turbines  may  be  embodied  in 
a  variety  of  types,  but  only  the  types  that  are  of  importance  in 
modern  turbine  practice  will  here  be  dealt  with. 

It  may  here  be  well  to  recall  some  of  the  laws  of  hydraulics 
or  the  mechanics  of  a  fluid: 

Water  stored  under  a  static  head  or  pressure  contains  a  cer- 
tain amount  of  energy  in  the  potential  form.  To  make  this  energy 
available  for  the  development  of  power  the  static  head  or  pres- 
sure of  the  water  is  converted  into  velocity  hi  the  turbine;  that 
is,  the  potential  energy  is  converted  into  kinetic  energy  and  it 
is  the  duty  of  the  turbine  to  absorb  this  kinetic  energy  either 
by  reaction  or  action  or  by  both,  and  to  convert  the  energy  thus 
absorbed  into  power  and  to  discharge  the  water  as  an  inert  mass 
or  nearly  so,  leaving  only  enough  velocity  in  the  water  to  carry 
it  away  from  the  turbine.  It  will  therefore  be  seen  that  the  energy 

37 


38  MODERN  TURBINE  PRACTICE. 

contained  in  the  water  may  exist  either  in  the  potential  or  kinetic 
form  or  in  both  forms  and  part  or  the  whole  of  the  energy  may 
be  converted  from  one  form  into  the  other;  also  that  the  head 
may  exist  either  in  the  form  of  static  head,  which  is  pressure,  or 
in  the  form  of  velocity  or  in  both  forms,  and  that  pressure  can 
be  converted  into  velocity  and  velocity  into  pressure. 

It  should  be  noted  here  that  the  head  used  in  the  formula 
for  the  discharge  velocity  of  water,  \/2gH,  is  always  the  head 
available  or  effective  at  the  turbine  and  that  the  velocity  found 
by  this  formula  is  the  theoretical  velocity,  which  has  to  be  mul- 
tiplied by  the  coefficient  of  discharge  for  the  bucket,  nozzle,  or 
opening  to  obtain  the  actual  velocity.  For  example,  for  a  properly 
constructed  guide-bucket  the  coefficient  is  from  0.95  to  0.97, 
or  the  speed  of  the  water  is  from  0.95  to  0.97V 2gH. 

If  c  is  the  velocity  of  the  water  corresponding  to  the  avail- 
able head  and  ca  the  absolute  velocity  with  which  the  water 

leaves    the  runner-buckets,  then  of  all    the  energy  contained  in 

C2_c  2 

the  water  the    portion  absorbed    by  the    turbine    is  — ^-^  or 

c 

— T^:  therefore  ca  should  be  as  low  as  practicable. 

ti    , 

The  speed  of  the  runner  or  the  speed  factor  always  refers  to 
the  initial  or  entrance  rim  of  the  runner. 

Within  reasonable  limits  the  closer  the  vanes  are  spaced — that 
is,  the  greater  the  number  of  buckets  in  the  guide  and  runner — 
the  better  will  the  water  be  guided,  but  with  an  increase  in  the 
number  of  buckets  the  frictional  losses  in  guide  and  runner  are 
also  increased.  In  practice  it  is  usual  to  have  the  number  of 
runner-buckets  different  from  the  number  of  guide-buckets. 

The  Reaction  Turbine. — Suppose  a  narrow  vessel  rectangular 
in  plan  is  mounted  at  the  end  of  a  horizontal  arm,  which  latter 
is  fastened  to  a  vertical  shaft  free  to  revolve,  the  longer  dimen- 
sion of  the  vessel  being  tangential  to  the  circle  described  by  the 
vessel  when  turning  with  the  shaft.  Suppose  also  the  vessel  to 
be  filled  with  water,  then  there  is  a  hydrostatic  pressure  against 
the  sides,  the  pressure  against  opposite  sides  balancing  each  other. 
If  an  opening  is  provided  in  one  of  the  smaller  sides  and  at  the 
same  time  the  water  level  in  the  vessel  is  kept  constant  by  a  con- 


CLASSIFICATION  OF  TURBINES.  39 

tinuous  supply  of  water,  then  the  velocity  of  the  jet  of  water 
issuing  from  the  opening  will  be  ct  =  V2gH}  in  which  H  is  the 
head  of  water  in  feet,  above  the  centre  of  the  opening.  With  the 
water  flowing  out  of  the  opening  at  the  rate  of  Q  cu.  ft.  per 
second,  the  weight  of  water  discharged  is  62.3  Q  Ibs.  per 

62  30 
second  and  the  mass  of  this  is  -     —  .    To  give  to  this  mass  an 

\j 

acceleration  of  ct  ft.  per  second  requires  a  force  or  pressure  in 

t  r>    62.3Q 
Ibs.  of  P=  -  -ct. 

y 

This  force  P,  required  to  give  the  acceleration  ct  to  the  water 
jet,  exerts  an  equal  and  unbalanced  pressure  or  reaction  upon 
the  side  opposite  to  the  opening,  applied  at  a  place  corresponding 
to  the  centre  of  the  opening  and  tending  to  move  the  vessel  in 
a  direction  opposite  to  that  of  the  water  jet.  With  the  vessel 
moving  in  the  direction  opposite  to  that  of  the  jet  of  water  and 
with  the  speed  of  vt  ft.  per  second,  the  pressure  or  reaction  equals 

D    62.3Q, 


and  the  horse-power  developed  equals 

TTT3  P'Vt 

H'R=550' 

If  the  speed  of  the  vessel  is  equal  to  that  of  the  water  jet, 
or  Vt  =  ct,  then  the  theoretical  hydraulic  efficiency  would  be  100%; 
or,  in  other  words,  with  the  vessel  or  bucket  moving  at  the  same 
speed  as  the  water  jet,  but  in  opposite  direction,  the  water  has 
no  horizontal  motion  when  compared  with  a  stationary  point; 
that  is,  the  absolute  horizontal  velocity  would  be  ca  =  ct  —  vt  =  0,  and 
the  water  would  simply  be  left  behind  and  drop  vertically,  as  if 
the  bottom  were  pulled  out  from  under  it. 

Thus  for  a  hydraulic  motor,  as  here  described,  working  with 
reaction  only,  the  speed  of  the  vessel  for  the  best  or  theoret- 
ically perfect  hydraulic  efficiency  would  be  equal  to  the  speed 
of  the  water  jet,  or  vt  =  ct  =  \/2gH,  as  in  this  case  all  the  kinetic 
energy  is  taken  out  of  the  water  and  the  latter  discharged  quite 


40  MODERN  TURBINE  PRACTICE. 

motionless  or  dead.  The  speed  factor  for  such  an  ideal  reaction 
motor,  having  a  velocity  of  vt  =  \/2gH,  would  therefore  be  1. 

However,  from  the  formula  for  the  pressure  or  reaction  P, 
it  will  be  seen  that  with  the  speed  of  the  vessel  or  bucket  vt  equal 
to  the  speed  of  the  water  jet  ct,  the  pressure  P  becomes  zero, 
that  is,  such  an  ideal  reaction  motor  can  do  no  useful  work.1 

Segner's  and  Barker's  turbines2  were  hydraulic  motors  work- 
ing with  reaction  only  in  the  manner  here  outlined. 

The  reaction  turbine  is  also  sometimes  called  pressure  turbine. 

The  types  in  which  reaction  turbines  may  be  built  are  the 
axial  flow,  radial  outward  flow,  radial  inward  flow,  and  the  vortex 
or  American  type.  Only  the  inflow  and  vortex  types  are  con- 
sidered here. 

The  characteristic  of  the  reaction  turbine  is  that  the  water 
issues  from  the  guide-buckets  with  a  speed  smaller  than  that 
due  to  the  head,  or  c  <  \/2gH  •  that  is  to  say,  at  the  moment  the 
water  reaches  the  clearance,  only  part  of  its  head  is  in  the  form 
of  velocity  and  the  remainder  in  the  form  of  pressure.  In  the 
runner-buckets  this  remaining  pressure  is  also  converted  into 
speed,  so  that  the  water  when  issuing  from  the  runner-buckets 
has  attained  the  velocity  due  to  the  whole  head.  It  may  be 
well  here  to  consider  the  effect  of  water  flowing  through  the  runner- 
buckets  of  a  reaction  turbine.  For  this  purpose  let  us  assume 
the  runner  as  stationary,  neglecting  here  the  fact  that  the  usual 
bucket  angles  would  not  permit  the  water  to  flow  properly  into 
and  through  the  runner-buckets  if  the  runner  is  stationary.  Let 
us  also  suppose  that  one  half  of  the  head  of  the  water  is  converted 
into  velocity  in  the  guide-bukcets,  as  is  the  common  practice, 
then  the  speed  of  the  water  at  the  exit  from  the  guide-buckets 
or  the  clearance  would  be  c=V2gX0.5H  =  Q.7Q7V2gH,  and  the 
pressure  would  be  that  due  to  the  remaining  half  of  the  head. 
In  the  runner-buckets  the  water  is  deflected  from  the  discharge 
direction  of  the  guide-buckets  to  the  discharge  direction  of  the 
runner-buckets  or  through  an  angle  of  £=  180°— (0:4-7-).  (See 
Fig.  10.)  The  water  thus  works  by  action  while  flowing  through 
the  runner-buckets. 

1  Wood.     Turbines,  pp.  50  to  55.  2  Wood.     Turbines,  p.  48. 


CLASSIFICATION  OF  TURBINES.  41 

The  speed  c  of  the  water  at  the  clearance  is  increased  in  the 
runner-buckets  by  the  remaining  half  of  the  head  and  at  the  exit 
from  the  runner -buckets  this  speed  will -be  ct=\/(2gX0.5H)+c2>. 
or  as  c2  =  2gX0.5H,  we  have 

ct  =  \/2(20X0.5#)  =  1 .4142\/20X0.5# 


The  equation  c<  =  v  (2gXQ.5H)+c2  is  derived  from  the  funda- 
mental formula  for  accelerated  motion,  /=  —  X—  -  -,  as  follows,. 
the  factor  62.3  being  the  weight  of  water  per  cubic  foot: 


therefore  ct=\/(2gXQ.5H)+c2. 

From  this  it  will  be  seen  that  while  the  half  of  the  head  which 
is  the  first  to  be  converted  into  speed  gives  the  water  a  velocity 
of  c=0.707N/2<7/7,  the  remaining  half  of  the  head  only  adds  to 
this  velocity  the  amount  of  ct  —  c=0.293\/2<7#,  or  as  c:ct  —  c 
=  0.707:0.293=1:0.4142,  the  speed  added  by  the  remaining; 
half  of  the  head  is  only  0.4142  of  the  speed  due  to  the  half  of  the 
head  which  is  the  first  to  be  converted  into  velocity,  or,  in  other 
words,  the  discharge  velocity  of  water  varies  with  the  square 
root  of  the  head. 

This  is  due  to  the  fact  that  the  volume  of  water  accelerated 
per  second  for  each  square  foot  of  discharge  opening  of  the  guide- 
buckets  is  c  cu.  ft.,  while  the  volume  accelerated  for  each  square 
foot  of  discharge  opening  of  the  runner-buckets  is  c  +  ct  cu.  ft.,. 
thus  giving  the  same  proportion  as  the  accelerations,  but  inversed,, 


or  c:c  +  ct  =  c«-c:c=0.293:  0.707  =  0.4142:1. 

Therefore          0.707  ^2gHX  c  =  0.293V2gH 


42 


MODERN  TURBINE  PRACTICE. 


that  is  to  say,  the  amount  of  work  done  per  second  by  each  half  of 
the  head  is  the  same. 

The  water  thus  works  by  reaction  while  leaving  the  runner- 
buckets,  the  reaction  being  due  to  the  increase  in  the  velocity 
of  the  water  while  flowing  through  the  runner-buckets. 

With  the  runner  moving  at  its  proper  speed,  the  actual  velocity 
with  which  the  water  enters  the  runner-buckets  will  not  be  c, 
but  ce  =  c-smea,  if  the  entrance  angle  of  the  runner-buckets  /? 
is  90°  and  the  velocity  with  which  the  water  leaves  the  runner- 
buckets  will  be  correspondingly  decreased. 

The  proportion  of  the  work  done  by  action  and  reaction  is 
indicated  by  the  speed  factor,  as  the  higher  the  speed  factor  of 
a  turbine  the  greater  is  the  reaction,  while  a  turbine  works  with 
action  only  if  the  speed  factor  is  less  than  0.5.  The  proportion 
of  work  done  by  reaction  and  action  depends  entirely  on  the  shape 
of  the  guide-  and  runner-buckets  and  the  bucket  shape  in  turn 
depends  on  the  angles  a,  /?,  and  7-.  (See  Fig.  10.)  The  angles 


FIG.  10. — Diagram  of  Guide-  and  Runner-bucket,  showing  angles  and 

velocities. 

a,  /?,  and  f  of  reaction  turbines  are  interdependent,  and  if  one  is 
changed,  the  other  two  have  also  to  be  altered,  or  the  efficiency 


CLASSIFICATION   OF  TURBINES.  43 

and  proper  working  of  the  turbine  will  be  affected.  For  axial- 
flow  turbines  the  following  equation  has  to  be  observed  to  obtain 
the  best  efficiency:  cotang  a  =  cotang  /?  +  cotang  y.1  With  radial- 
flow  turbines,  the  diameter  of  the  initial  or  entrance  rim  D  and 
the  diameter  of  the  terminal  or  exit  rim  Dt  of  the  runner  have 
to  be  taken  into  consideration.  The  width  between  crowns  of 
radial  turbines  usually  increases  from  the  initial  rim  to  the  ter- 
minal rim,  and  this  has  also  to  be  considered.  If  W  is  the  width 
or  clear  space  between  crowns  at  the  initial  rim  of  the  runner 
and  Wt  at  the  terminal  rim,  then  we  have  for  radial  inward-flow 
turbines:2 

cotang  7-=  (-M      ~  (cotang  a-cotang  /?) 


(D\2  W 
IT)  *w* 

Also,  for  a  turbine  to  work  with  reaction,  angle  a  must  be 
less  than  one  half  of  angle  /?,3  or 


A  turbine  has  ceased  to  work  with  reaction  and  has  become 
an  action  turbine  if 


Again,  the  more  the  angle  /?  exceeds  2a  the  greater  will  be 
the  amount  of  reaction  with  which  the  turbine  is  working. 

Theoretically  reaction  turbines  require  no  guide-buckets,  as 
shown  by  Segner's  and  Barker's  turbines  above  mentioned,  but 
they  are  now  always  provided  with  guide-buckets. 

The  size  of  the  terminal  angle  of  guide-buckets  a  does  not 
affect  the  efficiency,  but  is  usually  made  as  small  as  practical  con- 
siderations will  permit  ;  that  is  to  say,  the  direction  of  the  water 

1  Taschenb.  Huette.,  vol.  1,  p.  735. 

2  Taschenb.  Huette.,  vol.  1,  p.  740. 

3  Mueller.     Francis-Turbinen.,  p.  70. 


44  MODERN  TURBINE  PRACTICE. 

at  exit  from  guide-buckets  is  as  nearly  a  tangent  to  the  runner 
as  practicable,  and  it  is  therefore  the  size  of  the  initial  angle  of 
the  runner-buckets  /?,  which  determines  the  amount  of  reaction 
and  the  speed  of  the  turbine. 

The  terminal  angle  of  the  runner-buckets  7-  should  be  made, 
for  best  efficiency,  as  small  as  practicable ;  that  is  to  say,  the  rela- 
tive direction  of  the  water  issuing  from  the  runner-buckets  should 
be  as  nearly  as  possible  a  tangent. 

However,  with  the  decrease  in  the  size  of  the  angles  a  and  f, 
the  clear-passage  areas  at  the  terminal  ends  of  the  guide-  and 
runner-buckets  decrease  also,  and  therefore  for  turbines  of  equal 
diameter  and  width  and  shape  of  crowns,  smaller  angles  a  and  f 
mean  smaller  water  capacity  or  power  of  the  turbine. 

European  practice  for  radial  inward-flow  turbines  is  to  make 
both  the  angles  a  and  /?  from  15°  to  24°,  but  circumstances  will 
often  require  these  angles  to  be  as  much  as  30°  or  even  larger. 

The  angle  of  the  actual  or  absolute  direction  of  the  water 
at  exit  from  the  runner-buckets  d  should  be  made,  for  best  effi- 
ciency, equal  to  90°  or  vt  =  ct-  cosine  7--  If  this  angle  is  made 
less  than  90°,  there  will  be  an  increased  loss  of  velocity-head  in 
the  discharged  water,  and  if  made  larger  than  90°,  there  will  be 
a  loss  due  to  the  runner-vanes  moving  out  of  the  way  of  the  water 
before  having  completely  accomplished  their  object  in  turning 
or  deflecting  the  water  into  the  proper  direction  for  discharge. 

The  greater  the  amount  of  reaction  with  which  a  turbine  is 
working,  the  greater  is  the  speed  of  the  runner,  as  may  readily 
be  seen  from  Fig.  10.  The  amount  of  reaction  with  which  a  tur- 
bine is  working  does  not  affect  its  efficiency. 

Therefore  to  obtain  the  highest  speed  with  a  given  head  and 
runner  diameter  a  reaction  turbine  with  a  large  angle  /?  would 
be  chosen,  and  to  get  the  lowest  speed  with  a  given  head  and 
runner  diameter  an  action  turbine  would  be  chosen. 

European  practice  for  standard  patterns  of  radial  inflow  tur- 
bines is  to  make  the  angle  /?  equal  to  90°  and  to  have  the  velocity 
and  the  pressure  of  the  water,  at  exit  from  guide-buckets  or  at 
the  clearance,  each  that  due  to  one  half  of  the  head,  or  speed  of 
water  c=v/2#X0.5#,  which  is  approximately  c=Q.71\/2gH,  and 
the  corresponding  speed  of  the  runner  at  the  entrance  rim  is 


CLASSIFICATION  OF  TURBINES.  45 

v  =  c-  cosine  a,    or    approximately    v  =  Q.Q7\/2gH}    which    would 
require  a  to  be  19J01. 

The  head  of  the  water  remaining  as  pressure  at  exit  of  guide- 
buckets  or  at  the  clearance  is  therefore 


The  loss  of  head  in  the  guide-buckets,  due  to  friction  and  the 
conversion  of  pressure  into  velocity,  will  vary,  according  to  con- 
ditions, between  6  and  10%  of  the  head  converted  into  velocity, 
and  the  actual  speed  of  the  water  at  .exit  from  guide-buckets 
therefore  will  be  c=0.95  to  0.97\/2^,  in  which  h  is  that  part 
of  the  head  which  is  converted  into  velocity,  or  for  reaction  tur- 
bines, ^pjnverting  one  half  of  the  head  into  velocity,  c=0.95  to 
0.97\/20  X 0.5^= 0.675  to  0.69V20F,  and  v=OM  to  Q.65V2gH. 

However,  the  amount  of  reaction  and  with  it  the  speed  factor 
varies  considerably  in  general  practice  and  the  speed  factor  may 
be  anywhere  above  that  of  limit  turbines,  or  about  0.50  up  to 
0.90  or  even  more,  but  usually  is  between  0.57  and  0.75. 

Below  are  given  the  speed  factors  for  some  types  of  inflow 
turbines : 

American  or  vortex  turbines:   0.70  to  0.77. 

American  or  vortex  turbines  of  French  manufacture:  0.68 
to  0.75. 

European  type,  standard  practice:    0.67. 

As  extreme  cases  may  be  mentioned  the  2500-H.P.  double 
turbine  shown  in  Fig.  25,  with  a  speed  factor  of  0.82,  and  the 
1000-H.P.  triple  turbine  seen  in  the  cross-section  of  power-house, 
Fig.  19,  with  a  speed  factor  of  0.925,  the  latter  being  perhaps 
the  highest  ever  used  in  modern  turbine  practice. 

The  speed  of  the  runner  at  the  terminal  rim  is  vt=-j~,  and 
the  corresponding  speed  of  the  water  at  exit  from  runner-buckets 

and  relative  to  these  buckets  is  ct  =  — ^ — ,  if  d  is  equal  to  90°. 

cosine  ~r 

1  Mueller.     Francis-Turbinen,  p.  78. 


46  MODERN  TURBINE   PRACTICE. 

The  velocity-head  corresponding  to  the  absolute  velocity 
with  which  the  water  leaves  the  runner-buckets  is  lost,  except 
such  portion  of  it  as  may  be  recovered  by  means  of  a  draft-tube; 
therefore  for  best  efficiency  this  absolute  speed  ca  should  be 
as  low  as  practicable  without  interfering  with  the  proper  work- 
ing of  the  turbine  ;  or,  in  other  words,  of  the  energy  contained  in 
the  water  before  entering  the  turbine,  as  much  as  possible  should 
be  absorbed  by  the  runner  before  the  water  is  allowed  to  escape. 

With  angle  d  equal  to  90°,  the  absolute  exit  velocity  is 
ca  =  vt  •  tang  f,  or  ca—ct-  sine  f,  but  this  velocity  increases  with 
both  a  decrease  or  an  increase  in  the  size  of  the  angle  d. 

With  turbines  working  in  the  air,  the  absolute  exit  velocity  ca 
may  be  very  low,  or  the  water  might  even  simply  drop  out  of 
the  runner-buckets  by  gravity,  but  for  turbines  working  under 
water  or  in  a  case,  some  speed  has  to  be  retained  in  the  discharge 
to  free  the  runner,  displace  the  surrounding  water,  overcome  the 
friction  and  carry  off  the  discharged  water,  as  otherwise  the  tur- 
bine would  be  working  against  a  back  pressure.1 

The  water  flowing  through  the  runner-buckets  of  a  reaction 
turbine  completely  fills  these  buckets,  at  least  with  the  turbine 
working  at  full  or  nearly  full  capacity. 

The  guide-  and  runner-buckets  must  be  formed  by  easy  curves 
and  all  changes  in  direction  and  speed  of  the  water  must  be  made 
gradually,  and  the  water  issuing  from  the  guide-buckets  must 
meet  the  vanes  of  the  runner-buckets  without  shock  or  impact. 
To  avoid  such  impact  the  following  equations  have  to  be  observed 
for  speeds  and  bucket  angles: 

v-sine  /? 
~ 


c-sine  (B  —  a) 
v=  -  :  -  n  —  ) 
sine  p 


v  sne  a 
ce-- 


sine  (/?— a)' 


1  Mueller.     Francis-Turbmen.,  pp.  76  and  86. 


CLASSIFICATION  OF  TURBINES.  47 

The  losses  of  energy  in  reaction  turbines  are  between  17  and 
27%  and  are  due  to:1 

Hydraulic  resistances 10  to  14% 

Velocity  of  water  discharged  from  turbine 3  ' '    7% 

Leakage  at  clearance 2  ' '    3% 

Shaft  friction 2"    3% 

Total  losses 17  to  27% 

The  remaining  energy  or  efficiency  would  therefore  be  between 
83  and  73%. 

The  effect  of  the  speed-regulating  gates  on  the  water  flowing 
through  a  radial  inflow  reaction  turbine  may  here  be  considered. 
Let  us  assume  the  turbine  to  be  running  with  the  gate  or  gates 
half  closed. 

1.  The  cylinder  gate  will  cause  the  jets  of  water  issuing  from 
the  guide-buckets    to  be  reduced  to  one  half  of  their  width  or 
axial  dimension,  while  the  thickness  of  the   jets  or  their  circum- 
ferential dimension  remains  the  same  for  all  gate-openings.     But 
in  the  runner-buckets  the  jets  will  spread  in  width  and  decrease 
in  thickness,  so  that  the  water  jets  do  not  fill  either  the  width 
or  the  circumferential  dimension  of  the  runner-buckets. 

2.  The  register-gate  will  cause  the  jets  of  water  issuing  from 
the  guide-buckets  to  be  reduced   to  one  half  of  then-  thickness, 
so  that  the  water  jets  while  filling  the  width  do  not  fill  the  cir- 
cumferential dimension  of  the  runner-buckets. 

3.  The  wicket    gate  will   cause  the  water  jets  issuing  from 
the  guide-buckets  to  be  reduced  to  one  half  of  their  thickness 
and  also  to  be  diverted  from  their  direction  of  flow  at  full  gate* 
denoted  by  a.  in  Fig.  10,  to  a  direction  tangential  to  a  circle,  which 
may  be  of  a  smaller,  equal,  or  larger  diameter  than  the  entrance 
rim  of  the  runner,  according  to  the  arrangement  of  the  wickets. 
If  the  circle  to  which  the  water  jets  are  tangential  is  of  a  larger 
diameter  than  the  entrance  rim  of  the  runner,  the  jets  will  evi- 
dently not  strike  the  runner  at  all,  but  will  flow  around  with  the 
runner  and  at  a  speed  exceeding  the  speed  of  the  latter,  and  it  is 
this  excess  of  speed  and  the  pressure  of  the  water  issuing  from 

1  Mueller.     Francis-Turbinen.,  p.  18. 


48  MODERN  TURBINE  PRACTICE. 

the  guide-buckets  which  force  the  water  into  the  runner-buckets. 
With  a  comparatively  small  entrance  angle  of  the  runner-buckets  /?, 
the  water  jets  will  not  fill  the  circumferential  dimension  of  these 
buckets,  while  with  a  comparatively  large  entrance  angle  ft,  the 
water  jets  will  fill  the  Tunner-buckets,  but  will  flow  through  them 
with  a  decreased  velocity,  the  decrease  in  velocity  being-  in  direct 
proportion  to  the  decrease  in  the  volume  of  water  admitted  by 
the  regulating-gates. 

From  the  above  considerations  the  following  conclusions  may 
be  drawn: 

A  reaction  turbine  working  with  part  gate  and  having  the 
runner-buckets  not  completely  filled  with  water  will  work  with 
action  only,  the  reaction  effect  being  lost,  and  there  will  be  no 
pressure  at  the  clearance,  except  the  slight  amount  required  to 
overcome  the  friction  and  the  centrifugal  force  of  the  water,  and 
thus  cause  it  to  enter  the  runner-buckets. 

A  reaction  turbine  working  with  part  gate  and  with  action 
only  will  give  a  lower  efficiency  with  such  part  gate  than  a  tur- 
bine designed  to  work  with  action  only  at  all  gate-openings ;  that 
is,  an  action  turbine. 

As  there  is  practically  no  pressure  at  the  clearance  of  a  reac- 
tion turbine  when  working  with  part  gate  and  with  action  only, 
the  water  will  issue  from  the  guide-buckets  with  a  speed  almost 
as  great  as  the  speed  due  to  the  whole  head  or  c=\/2gH,  and 
therefore  the  percentage  of  the  volume  of  water  passed  by  such 
part  gate-openings  is  greater  than  the  percentage  of  the  gate- 
opening  itself.  For  example,  a  reaction  turbine  in  which  the 
water  issues  from  the  guide-buckets  with  a  velocity  of  c= 
V2gXQ.5H  at  full  gate  would  pass  at  fuU  gate  G.7lV2gH  cu.  ft. 
of  water  per  square  foot  of  discharge  opening  of  the  guide-buckets. 
The  same  turbine,  when  running  with  half  gate-opening  would 
pass  Q.5V2gH  cu.  ft.  of  water  per  square  foot  of  discharge  open- 
ing of  the  guide-buckets,  or  the  water  passed  at  full  and  half  gate 
would  be  as  1:0.71. 

The  effect  of  the  water  completely  filling  the  runner-buckets 
of  a  reaction  turbine,  but  flowing  through  these  buckets  at  a 
reduced  speed,  when  running  with  part  gate,  will  be  referred  to 
in  connection  with  the  effect  of  throttling-gates. 


CLASSIFICATION  OF  TURBINES.  49 

The  principal  advantages  of  the  reaction  turbine  are: 

The  turbine  gives  a  good  hydraulic  efficiency. 

The  hydraulic  efficiency  is  the  same  with  the  turbine  working 
in  the  air  or  under  water  or  in  a  case.  It  should  here  be  noted, 
however,  that  the  mechanical  efficiency  of  the  turbine  will  be 
from  1J  to  2J%  less  when  working  under  water  or  in  a  case  than 
when  working  in  the  ah*,  owing  to  the  friction  of  the  runner  in 
the  water. 

Part  of  the  head  may  be  utilized  by  means  of  a  draft-tube 
without  affecting  the  efficiency. 

With  a  given  head  and  runner  diameter,  the  reaction  turbine 
may  be  designed  to  give  up  to  twice  the  speed  or  number  of  revo- 
lutions obtainable  with  the  action  turbine,  which  is  of  advantage 
in  connection  with  low  heads. 

With  a  given  head  and  runner  diameter,  the  speed  or  num- 
ber of  revolutions  of  the  reaction  turbine  may  be  varied  between 
wide  limits  without  affecting  the  efficiency  by  varying  the  bucket 
angles. 

The  principal  disadvantages  of  the  reaction  turbine  are: 

The  regulating-gates,  to  give  good  efficiency  with  part  gate- 
opening,  have  to  be  much  more  complicated  than  those  of  action 
turbines,  and  even  then  the  efficiency  with  small  gate-openings  is 
less  than  for  action  turbines. 

The  turbine  does  not  give  a  good  hydraulic  efficiency  if  used 
as  a  partial  turbine,  and  can  therefore  not  well  be  utilized  for  high 
heads, 

The  water  while  passing  the  clearance  is  under  pressure,  which 
means  leakage  of  water  and  thus  reduction  in  efficiency. 

The  Action  Turbine. — It  will  be  obvious  to  every  one  that  a 
jet  of  water  striking  a  stationary  or  relatively  stationary  sur- 
face and  being  deflected  by  the  latter  will  exert  a  pressure  against 
that  surface,  the  pressure  being  the  greater  the  greater  the  angle  is 
through  which  the  jet  is  deflected.  If  P  is  the  pressure  in  pounds 
exerted  by  a  water  jet  against  a  surface,  such  as  a  bucket  of  an 
impulse  turbine,  and  e  is  the  angle  through  which  the  jet  is  deflected, 

62  3Q 

then  P=~     —(c—v)(l  —  cosine  e),  in  which  v  is  the  speed  of  the 

i/ 

buckets   at   the  bucket   circle   and   62.3  the  weight   of   a   cubic 


50  MODERN  TURBINE  PRACTICE. 

foot  of  water.  The  minimum  and  maximum  values  for  P  would 
be  with  e  equal  to  zero  or  no  deflection  and  e  equal  to  180° — that 
is,  reverse  of  direction — or 


0°)=0 
y 

and 


The  horsepower    of  the  impulse  turbine  would  therefore  be 

Pv 

equal  to  H.P.  =  =;. 
oou 

For  best  efficiency  the  theoretical  speed  of  a  hydraulic  motor 
working  with  action  only  would  be  equal  to  one  half  the  speed 
of  the  water  or  0.5\/2##;  that  is  to  say,  the  speed  factor  would 
be  0.5.  This  will  at  once  be  seen  from  the  following  considera- 
tions :  If  the  speed  of  the  bucket  circle  of  an  impulse-  turbine  is 
one  half  the  speed  of  the  water  or  v  =  Q.5c,  then  the  water  strikes 
the  buckets  with  a  velocity  relative  to  the  buckets  of  ce=c—v  =  Q.5c, 
and  being  deflected  by  the  buckets  through  180° — that  is,  reversed 
— leaves  the  buckets  with  the  same  relative  speed,  or  cf  =  ce=0.5c, 
and  travels  in  the  opposite  direction,  or  backward,  at  that  speed. 
It  will  therefore  be  obvious  that  the  water  leaving  the  buckets 
and  traveling  backwards  with  a  realtive  speed  of  c^  =  0.5c,  the 
buckets  at  the  same  time  traveling  forward  with  a  speed  of  v=Q.5c, 
will  have  an  absolute  speed  of  ct— v=0,  or,  in  other  words,  the 
water  has  been  brought  to  rest,  compared  with  some  stationary 
point,  and  as  all  the  energy  in  the  water  had  been  in  the  form  of 
kinetic  energy,  all  the  energy  has  been  absorbed  by  the  runner. 

Action  turbines  are  also  often  called  pure  action  turbines  or 
action  turbines  with  free  deviation,  to  distinguish  them  from 
the  action  turbines  with  limited  buckets.  The  types  in  which 
such  turbines  may  be  built  are  the  axial-flow,  radial  outward- 
flow,  and  radial  inward-flow  types,  which  may  all  be  either  full 

1  Taschenb.  Huette.,  vol.  1,  p.  262. 


CLASSIFICATION  OF  TURBINES.  51 

or  partial  turbines,  also  the  impulse  and  the  spoon  types,  the  latter 
resembling  in  its  features  both  the  radial  outward-flow  and  the 
impulse  types.  Only  the  outflow  and  impulse  types  are  considered 
here. 

The  characteristic  of  the  action  turbine  is  that  the  water  issues 
frem  the  guide-buckets  or  nozzle  with  the  full  velocity  due  to 
the  head,  or  c=\/2gH;  that  is  to  say,  at  the  moment  the  water 
leaves  the  guide-buckets  or  nozzle  all  the  pressure  or  potential 
energy  of  the  water  has  been  converted  into  kinetic  energy  and 
the  turbine  therefore  works  with  action  only. 

Much  that  has  been  said  about  the  reaction  turbine  applies, 
also  to  the  action  turbine. 

For  outflow  action  turbines  the  angles  a  and  /?  are  usually 
made  2a=/?,  but  /?  may  also  be  smaller  than  2a.  The  angles 
a  and  7-  should  be  as  small  as  practicable — that  is,  each  should 
be  as  nearly  a  tangent  as  possible — for  the  reason  that  the  smaller 
a  and  /?,  the  greater  is  the  angle  of  total  deflection  of  the  water 
and  therefore  the  greater  is  the  efficiency,  the  angle  of  total  deflec- 
tion being  e  =  180  ~  (a  -f  7-) . 

European  practice  is  to  make  a  about  12°  and  f  about  13^ 
for  high  heads  and  small  volumes  of  water,  increasing  to  a  about 
30°  and  7-  about  28°  for  low  heads  and  large  volumes  of  water. 

The  angle  of  the  actual  or  absolute  direction  of  the  water, 
at  exit  from  the  runner-buckets  d,  shpuld  be  made,  for  best  effi- 
ciency, equal  to  90°  or  vt  =  ct-  cosine  7-.  If  this  angle  is  made 
less  than  90°,  there  will  be  an  increased  loss  of  velocity-head  in 
the  discharged  water,  and  if  made  larger  than  90°,  there  will  be 
a  loss  due  to  the  runner-vanes  moving  out  of  the  way  of  the  water, 
before  having  completely  accomplished  their  object  in  turning 
or  deflecting  the  water  into  the  proper  direction  for  discharge. 

Impulse  turbines  may  be  regarded  as  action  turbines;  for 
example,  an  impulse  turbine  deflecting  the  water  sidewise,  that 
is  in  a  more  or  less  axial  direction  like  the  Pelton,  may  be  regarded 
as  a  partial  action  turbine  having  on  the  same  shaft  two  runners 
of  the  axial-flow  type,  placed  in  close  contact  with  their  inlet 
or  entrance  sides,  discharging  axially  in  opposite  directions  and 
having  a  larger  bucket  spacing  than  used  for  the  common  axial- 
flow  type.  There  are  also  no  crowns,  the  radial  spreading  of  the 


52  MODERN  TURBINE  PRACTICE. 

water- jet  being  prevented  by  raised  edges  on  the  buckets,  while 
each  nozzle  takes  the  place  of  a  guide-bucket. 

For  properly  designed  impulse  turbines  the  angle  a  should 
be  only  a  few  degrees,  thus  giving  a  high  efficiency,  while  the 
angle  7-  measured  in  the  plane  in  which  the  water- jet  is  deflected 
varies  according  to  the  shape,  size,  and  spacing  of  the  buckets 
and  the  diameter  of  the  bucket  circle,  as  the  angle  7-  has  to  be 
large  enough  that  the  jet  leaving  a  bucket  will  clear  the  bucket 
following. 

The  diameter  of  the  bucket  circle  should  not  be  less  than 
twelve  times  the  diameter  of  the  nozzle  discharge-opening  for 
a  round  nozzle,  or  the  diameter  of  a  circle  equal  in  area  to  the 
discharge-opening  of  a  rectangular  nozzle. 

The  loss  of  head  in  the  guide-buckets  or  nozzle,  due  to  fric- 
tion and  the  conversion  of  pressure  into  velocity,  will  vary,  accord- 
ing to  conditions,  between  6  and  8%  of  the  head,  and  the  speed 
of  the  water  at  exit  from  guide-buckets  or  nozzle  therefore  will 
be  c= 0.96  to  0.97\/2##.  In  straight  smooth  nozzles  of  impulse 
turbines  the  loss  of  head  will  not  be  greater  than  4  to  6%  and 
the  speed  of  the  water  therefore  c=0.97  to  0.98\/2pr. 

The  actual  speed  of  the  runner  of  turbines  of  European  design 
is  for  outflow  action  turbines  v— 0.43  to  QA7\^2gH}  and  for  impulse 
turbines  the  actual  speed  at  the  bucket  circle  is  t>  =  0.44  to 
QA7\/2gH. 

The  best  efficiency,  the  absolute  speed  ca,  with  which  the 
water  leaves  the  runner-buckets  should  be  as  low  as  practicable, 
without  interfering  with  the  proper  working  of  the  turbine;  or, 
in  other  words,  of  the  energy  contained  in  the  water  before  enter- 
ing the  turbine,  as  much  as  possible  should  be  absorbed  by  the 
runner  before  the  water  is  allowed  to  escape. 

With  the  angle  §  equal  to  90°,  the  absolute  exit  velocity  is 
c0=/yrtang  f  or  ca=crsine^,  but  this  velocity  increases  with 
both  a  decrease  or  an  increase  in  the  size  of  the  angle  ft. 

The  water  flowing  through  a  runner-bucket  of  an  action  tur- 
bine with  free  deviation  does  not  completely  fill  this  bucket,  but 
shoots  along  the  face  of  the  vane,  leaving  an  empty  space  between 
the  water  and  the  back  of  the  next  vane.  A  ventilation  has  to 
be  provided  for  this  empty  space,  either  through  the  inlet-  or 


CLASSIFICATION  OF  TURBINES.  53 

entrance-opening  of  the  bucket  or  through  holes  properly  located 
in  the  crowns  of  the  runner,  as  otherwise  this  empty  space  would 
fill  with  dead  water,  which  would  seriously  interfere  with  the  proper 
working  of  the  turbine  and  thus  reduce  the  efficiency. 

As  for  good  efficiency  all  action  turbines  have  to  work  in  the 
air,  the  absolute  exit  velocity  ca  may  be  very  low,  or  the  water 
might  almost  simply  drop  out  of  the  runner-buckets  by  gravity. 

The  guide-  and  runner-buckets  must  be  formed  by  easy  curves 
and  all  changes  in  direction  made  gradually.  All  changes  in 
speed  in  the  guide-buckets  or  nozzle  must  be  made  gradually. 
The  water  issuing  from  the  guide-buckets  of  an  action  turbine 
must  meet  the  vanes  of  the  runner-buckets  without  shock  or 
impact,  and  to  avoid  such  impact  the  following  equations  have 
to  be  observed  for  speeds  and  bucket  angles: 

_c-sine  (f—a)^  v  sine  a 

sine/?  Ce~sine  (/?-«)' 

The  principal  advantages  of  the  action  turbine  are: 

The  turbine  gives  a  good  hydraulic  efficiency.  The  regu- 
lating-gates are  very  simple  and  the  turbine  gives  a  good  hydraulic 
efficiency  even  with  small  gate-openings. 

The  turbine  gives  almost  as  high  an  efficiency,  if  built  as  a 
partial  turbine,  as  if  built  as  a  full  turbine. 

With  a  given  head  and  runner  diameter  the  action  turbine 
gives  the  lowest  speed  or  least  number  of  revolutions  of  any  class 
of  turbine,  which  is  of  advantage  in  connection  with  high  heads. 

With  a  given  head  and  volume  of  water  the  number  of  revo- 
lutions of  the  action  turbine  may  be  varied  between  wide  limits 
by  varying  the  runner  diameter  and  building  the  turbine  as  a 
full  or  partial  turbine,  as  the  runner  diameter  and  volume  of 
water  may  demand. 

The  water,  while  passing  the  clearance,  is  not  under  pressure, 
therefore  no  water  is  wasted  by  leakage  at  the  clearance. 

The  principal  disadvantages  of  the  action  turbine  are: 

The  turbine  must  always  work  in  the  air,  as  when  working 
under  water  the  runner-buckets  cannot  be  ventilated  and  conse- 
quently the  efficiency  is  much  reduced. 


54  MODERN  TURBINE  PRACTICE. 

If  a  draft-tube  is  to  be  used  in  connection  with  an  action  tur- 
bine, an  air-admission  valve  has  to  be  provided  to  supply  the 
air  for  ventilating  the  runner-buckets  and  to  regulate  the  water 
level  in  the  turbine-case  or  draft-tube,  so  as  to  be  always  below 
and  clear  of  the  lowest  point  of  the  bucket-ring  of  the  runner. 

The  Limit  Turbine. — The  limit  turbine  is  usually  considered 
as  an  action  turbine  and  therefore  also  called  action  turbine  with 
limited  buckets,  but  as  a  matter  of  fact  the  limit  turbine  stands 
in  the  middle  or  forms  the  dividing  line  between  the  action  and 
reaction  turbine. 

The  types  in  which  limit  turbines  may  be  built  are  the  axial- 
flow,  radial  outward -flow,  and  radial  inward-flow  types,  but  the 
inflow  turbine  appears  to  be  the  most  promising  and  therefore 
the  type  that  will  be  most  generally  used  in  the  future. 

The  limit  turbine,  combining  as  it  does  many  of  the  advan- 
tages of  both  the  action  and  the  reaction  turbine,  has  as  yet  not. 
received  the  attention  which  it  deserves,  and  it  is  to  be  hoped 
that  this  turbine  will  soon  find  a  more  extended  application. 

The  characteristic  of  the  limit  turbine  is  that,  even  if  designed 
to  work  with  action  only,  the  water  flowing  through  the  runner- 
buckets  completely  fills  these  buckets,  at  least  with  the  turbine 
working  at  full  or  nearly  full  capacity.1 

Most  of  what  has  been  said  about  the  action  and  reaction 
turbines  applies  also  to  the  limit  turbine. 

The  angles  a  and  /?  for  limit  turbines  working  with  action 
only  are  made  2a=/?,  but  /?  may  also  be  made  larger,  up  to  about 
2a  +  10°=/?,  tnus  giving  the  turbine  a  slight  amount  of  reaction. 
Angles  a  and  7-  are  made  as  small  as  practicable  and  d  is  made 
90°  or  slightly  more  or  less,  the  same  as  stated  for  action  tur- 
bines. The  loss  of  head  in  the  guide-buckets  is  from  6  to  8%,. 
as  given  for  action  turbines  and  the  actual  speed  of  the  runner 
of  limit  turbines  is  v  =  0.48  to  OA9V2gH. 

The  absolute  discharge  velocity  ca  may  be  very  low  for  tur- 
bines working  in  air,  but  for  turbines  working  in  water,  ca  must 
be  sufficient  to  free  the  turbine  from  the  discharged  water. 

The  guide-  and  runner-buckets  must  be  formed  by  easy  curves, 

1  Meissner      Hydraulische  Motoren,  vol.  2,  p.  321. 


CLASSIFICATION  OF  TURBINES.  55 

changes  in  direction  and  speed  of  the  water  must  be  made  gradu- 
ally, and  the  general  curvature  and  the  clear  areas  at  different 
points  of  the  runner-buckets  must  be  such  as  not  to  force  the 
water-jet  from  its  natural  shape.  To  avoid  the  impact  of  the 
water  against  the  vanes  of  the  runner-buckets,  the  following 
equations  have  to  be  observed: 


c-sne      —  «  t>-sne  a 


sine  ft  sine  (/?—«)' 

The  principal  advantages  of  the  limit  turbine  are:  The  tur- 
bine gives  a  good  hydraulic  efficiency.  The  hydraulic  efficiency 
is  the  same  with  the  turbine  working  in  the  air  or  under  water 
or  in  a  case,  although  the  mechanical  efficiency  will  be  from  1J 
to  2J%  less  when  working  under  water  or  in  a  case  than  when 
working  in  the  air,  owing  to  the  friction  of  the  runner  in  the  water. 

Part  of  the  head  may  be  utilized  by  means  of  a  draft-tube 
without  affecting  the  efficiency. 

Very  simple  regulating-gates  may  be  used,  and  the  turbine 
gives  a  good  hydraulic  efficiency  even  with  small  gate-openings. 

The  turbine  gives  nearly  as  high  an  efficiency,  if  built  as  a 
partial  turbine,  as  if  built  as  a  full  turbine,  but  a  partial  limit 
turbine  must  always  work  in  the  air  and  if  working  in  a  case, 
with  draft-tube,  an  air-admission  valve  has  to  be  provided  to 
keep  the  water  level  in  the  case  or  draft-tube  below  the  lowest 
point  of  the  runner,  as  otherwise  the  efficiency  would  be  reduced. 
With  a  given  head  and  runner  diameter  the  limit  turbine  gives  a 
speed  or  number  of  revolutions  almost  as  low  as  the  action  tur- 
bine, which  is  of  advantage  hi  connection  with  high  heads.  With 
a  given  head  and  volume  of  water,  the  number  of  revolutions 
of  the  limit  turbine  may  be  varied  between  wide  limits  by  vary- 
ing the  runner  diameter  and  building  the  turbine  as  a  full  or 
partial  turbine  as  the  runner  diameter  and  volume  of  water  may 
demand. 

The  water  while  passing  the  clearance  is  under  little  or  no 
pressure,  therefore  little  or  no  water  is  wasted  by  leakage  at  the 
clearance. 

The  following  table  gives  a  comparison  of  the  power  developed 


56 


MODERN  TURBINE  PRACTICE. 


by  different  designs  of  inflow  turbines,  all  working  under  the 
same  head  of  1  meter  (3.28  ft.)  and  running  at  74  revolutions 
per  minute.1  The  original  metric  measure  has  been  retained 
to  avoid  odd  fractions.  The  vortex  turbine  is  of  European  design; 
that  is,  a  modification  of  the  American  type  of  turbines  and  the 
high-  and  medium-speed  inflow  turbines  are  reaction  turbines  like 
the  vortex.  The  dimensions  given  are,  of  course,  for  the  entrance 
rim  of  the  runner. 


Diameter 

Width 

of 

between 

Design. 

Runner, 
in  Milli- 

Crowns, 
in  Milli- 

Horse- 
power. 

Efficiency. 

meters. 

meters. 

Vortex  turbine 

1000 

550 

19    1 

75% 

High-speed  inflow  turbine  
Medium-speed  inflow  turbine  

700 
700 

150 
100 

3.88 
1.87 

82% 
80% 

Limit  turbine    .  .        

600 

50 

0  58 

75% 

This  table  shows  that  the  high-speed  inflow  reaction  turbine 
gives  the  best  efficiency,  the  efficiency  decreasing  for  designs 
having  a  higher  or  lower  speed  or  giving  a  greater  or  smaller  power; 
also,  for  turbines  working  under  the  same  head  the  table  shows 
that: 

With  a  given  number  of  revolutions  the  vortex  turbine  gives 
the  greatest  and  the  limit  turbine  the  least  power. 

With  a  given  power  the  vortex  turbine  gives  the  highest 
and  the  limit  turbine  the  lowest  number  of  revolutions. 


1  Zeitsch  d.  V.  deutsch.  Ing.,  June  13,  1903,  p.  846. 


CHAPTER  IV. 

/ 

STEAM-TURBINES. 

As  is  well  known  to  engineers,  the  first  reaction  steam-tur- 
bine was  invented  about  120  B.C.  by  Heron,  a  Greek  living  at 
Alexandria,  Egypt,  and  the  first  action  steam-turbine  of  the 
impulse  type  was  invented  by  Giovanni  Branca,  an  Italian,  in 
the  year  1629.  Both  these  devices  may  be  regarded  merely  as 
toys,  and  it  was  only  during  the  last  two  decades  of  the  nineteenth 
century  that  steam-turbines  were  developed  into  commercial 
machines.  However,  this  development  has  been  a  rapid  one, 
as  both  the  physical  properties  of  the  steam  and  the  laws  govern- 
ing the  action  of  a  fluid  in  a  turbine  were  well  known.  Thus  in 
less  than  twenty  years  the  steam-turbine  has  been  advanced 
from  a  toy  to  a  machine  which,  running  condensing,  gives  a  steam 
efficiency  superior  to  a  high-grade  compound  condensing  Corliss 
engine  of  the  same  power. 

It  is  not  the  writer's  intention  here  to  enter  into  the  thermo- 
dynamic  conversion  of  energy,  but  simply  to  consider  the  mechan- 
ical action  of  steam  in  a  turbine.1 

In  general  it  may  be  stated  that  the  same  laws  and  principles 
governing  hydraulic  action  and  reaction  turbines  apply  also  to 
turbines  working  with  any  other  fluid,  either  liquid  or  gaseous; 
but  due  consideration  must  be  given  to  the  differences  in  physical 


1  For  an  exhaustive  study  of  the  steam-turbine,  the  excellent  work  by 
Dr.  A.  Stodola,  "Steam  Turbines,"  New  York,  1905,  is  strongly  to  be 
recommended.  This  book  not  only  treats  fully  on  the  theory  and  practice 
of  the  steam-turbine  and  the  thermodynamic  principles  involved,  but  also 
describes  and  illustrates  the  different  types  of  turbines  manufactured,  and 
gives  direction  for  designing  and  calculating  the  dimensions  of  the  vari- 
ous types  of  steam-turbines. 

57 


58  MODERN  TURBINE  PRACTICE. 

properties  of  liquid  and  gaseous  fluids.  Taking  water  and  steam 
as  examples  of  liquid  and  gaseous  fluids,  although  saturated  steam 
is  not  a  true  gas,  the  following  three  principal  differences  in  phys- 
ical properties  will  be  found. 

1.  Water  acting  in  a  turbine  has,  for  all  practical  purposes, 
always  the  same  weight  per  cubic  foot;  that  is,  water  is  not  expan- 
sive, while  steam  is  expansive,  changing  its  volume  and  density 
or  weight  per  cubic  foot  with  every  change  in  pressure  and  tem- 
perature. 

If  p  is  the  pressure  in  pounds  per  square  inch  above  the  vacuum 
or  the  absolute  pressure,  t  the  temperature  Fahrenheit,  and  0.622 
the  specific  density  of  gaseous  steam,  that  of  air  being  one,  then 
we  have: 

Weight  in  pounds  per  cubic  foot  or  density  of  steam: 
Saturated  steam  L=jj^.  -. 

,     2.7074pX  0.622 

Gaseous,  that  is  highly  superheated,  steam  L= /^       . 

4oy.J  T- 1 

Volume  in  cubic  feet  per  pound  of  steam: 
Saturated  steam  V=    QQ41  . 

459.2 +  f 


Gaseous,  that  is  highly  superheated,  steam  V= 


2.7074^X0.622' 


2.  The  pressure  or  head  of  the  water  is  directly  due  to  its 
weight,  while  the  pressure  of  steam  is  due  to  its  expansive  force 
produced  by  the  quantity  of  heat  contained  in  the  steam,  but 
the  pressure  per  square  inch  may  also  be  considered  as  a  head. 
This  head  is  equal  to  the  height  in  feet  of  a  column  of  steam 
having  an  area  of  base  of  1  sq.  in.  and  a  uniform  density  corre- 
sponding to  the  given  absolute  initial  pressure,  the  weight  of 
which  column  is  equal  to  the  given  difference  between  initial 
and  exhaust  steam  pressure  per  square  inch,  or  head  of  steam 

in  feet  H= ^    ^    ,  in  which  pi  is  the  exhaust  or  back  pres- 

Li 

sure.     In  an  analogous  manner  the   atmospheric   back  pressure 


STEAM-TURBINES.  59 

against  which  a  hydraulic  turbine  is  discharging  may  be  partly 
removed  or  a  partial  vacuum  produced  by  the  weight  of  a  hang- 
ing water  column  in  a  draft-tube,  while  the  atmospheric  back 
pressure  against  which  a  steam-turbine  is  exhausting  may  be 
partly  removed  by  removing  part  of  the  quantity  of  heat  con- 
tained in  the  steam  by  means  of  condensation. 

3.  Water  under  any  pressure  or  head  will  flow  out  of  a  nozzle 
with  a  velocity  of  c=V2gH.  The  velocity  of  steam  flowing 
from  a  greater  absolute  pressure  p  into  an  atmosphere  of  a  less 
absolute  pressure  p\  increases  as  the  difference  in  pressure  increases. 
Following  the  same  general  law  as  the  velocity  of  water,  or  c=\/2gH, 
and  substituting  for  H  its  equivalent  as  given  above,  we  have  * 

— — j — — .     However,  this   law   only  applies   as   long 

as  the  external  pressure  pi  is  58%  or  more  of  the  absolute  internal 
pressure  p,  or  pi  >  0.58p,  and  the  velocity  of  the  steam  shows 
practically  no  further  increase  with  the  fall  of  the  external  pres- 
sure below  58%  of  the  internal  pressure  even  to  the  extent  of 
a  perfect  vacuum.  In  flowing  through  a  nozzle  of  the  best  form, 
steam  expands  to  the  external  pressure  so  long  as  it  is  not  less 
than  58%  of  the  internal  pressure.  For  an  external  pressure 
of  58%  and  for  lower  percentages,  the  ratio  of  expansion  in  the 
nozzle  is  1  to  1.624. 

It  will  therefore  be  seen  that  the  velocity  of  steam  flowing 
out  of  a  nozzle  or  opening  is  due  both  to  the  pressure  and  the 
expansion  of  the  steam. 

The  following  is  a  general  consideration  of  the  steam-turbine 
and  its  advantages  and  disadvantages,  especially  as  compared 
with  reciprocating  steam-engines. 

Theoretically  a  jet  of  steam  issuing  from  a  properly  designed 
nozzle  will  develop  as  much  energy  as  if  the  same  steam  were 

1  The  equation  here  given  for  c  expresses  the  general  law  for  the  outflow 
of  gases,  and  in  particular  holds  true  for  the  outflow  of  atmospheric  air, 
but  does  not  give  accurate  results  when  applied  to  steam.  Grashof's  for- 
mulas for  the  outflow  of  steam  are  considered  as  the  most  accurate.  However, 
as  these  formulas  are  very  intricate,  they  are  not  given  here,  but  may  be 
found  in  Grashof's  "Theoretlsche  Maschinenlehre,"  vol.  1,  paragraphs  111 
to  113;  also  in  Taschenb.  Huettc.,  vol.  1,  p.  289. 


CIVIL  ENGINEERING 


60  MODERN  TURBINE  PRACTICE. 

expanded  behind  an  engine-piston,  but  in  a  turbine  expansion 
can  be  carried  much  further  than  it  is  practicable  in  an  engine. 
With  a  reciprocating  engine  there  is  no  gain  in  efficiency  to  be 
secured  by  expanding  the  steam  to  less  than  5  or  6  Ibs.  absolute 
pressure  on  about  20  to  18  his.  of  vacuum,  as  not  only  would 
the  low-pressure  cylinder  become  very  large  and  thus  the  fric- 
tion loss  very  great,  but  as  each  end  of  the  cylinder  is  alter- 
nately connected  with  the  steam-inlet  and  the  exhaust  and  the 
exhaust  temperature  is  very  low  with  a  high  vacuum,  the  cylinder 
condensation  and  re-evaporation  will  be  correspondingly  high 
and  the  loss  greater  than  the  gain  due  to  further  expansion.  In 
a  steam-turbine,  a  back  pressure  as  low  as  1  or  2  Ibs.  absolute, 
or  about  28  to  26  ins.  of  vacuum,  can  be  easily  obtained,  as  there 
is  no  increased  friction  loss  due  to  a  high  vacuum,  nor  is  there 
the  loss  due  to  condensation  and  re~evaporation,  as  the  steam 
in  a  turbine  always  flows  in  the  same  direction,  while  on  the  other 
hand,  according  to  the  Carnot  cycle,  a  low  exhaust  pressure  and 
temperature  means  a  high  thermal  efficiency,  or 


in  which  T\  is  the  absolute  inlet  and  T2  the  absolute  exhaust 
temperature. 

The  steam-turbine  also  shows  a  much  higher  economy  with 
light  and  overloads  than  the  reciprocating  engine,  and  this  is 
especially  the  fact  when  the  turbine  is  run  condensing  and  is. 
then  due,  in  a  large  measure,  to  the  high  vacuum  that  is  used 
in  connection  with  turbines.  Steam-turbines  will  operate  econom- 
ically with  loads  of  from  50%  to  125%  of  the  full  load,  and  in  some 
types  even  with  from  25%  to  150%  of  the  full  load. 

The  steam-turbine  shows  a  considerable  gain  in  economy 
when  using  superheated  steam,  and  this  is  almost  entirely  due,, 
according  to  Prof.  Thurston,  to  the  reduction  of  the  surface  or 
skin  friction  between  the  vanes  and  the  steam.  As  there  are 
no  interior  rubbing  or  wearing  surfaces,  stuffing-boxes  or  packings, 
etc.,  requiring  lubrication  and  exposed  to  the  live  steam,  super- 
heated steam  of  much  higher  temperature  may  be  used  than  is 


STEAM-TURBINES.  61 

advisable  with  reciprocating  engines,  and  owing  to  the  absence 
of  interior  lubrication  the  condensed  steam  may  be  returned 
directly  to  the  boiler,  which  is  especially  of  advantage  in  con- 
nection with  marine  steam-turbines.  The  absence  of  interior 
rubbing  surfaces  does  away  with  the  friction  and  wear  of  the 
principal  working  parts. 

'The  steam-turbine  has  few  working  parts,  the  motion  is  rotary 
and  the  power  directly  applied,  the  torque  or  turning  moment 
is  uniform  and  the  speed  is  uniform  for  all  parts  of  the  revolu- 
tion and  therefore  is  smooth-running  and  free  from  vibrations, 
thus  requiring  little  or  no  foundations. 

The  steam-turbine  is  compact,  requires  little  space,  and  is 
easily  and  cheaply  installed. 

Owing  to  the  high  velocity  with  which  steam  issues  from, 
nozzles  or  guide-buckets,  the  speed  of  steam-turbines  is  also  very 
high,  and  while  this  is  an  advantage  in  driving  dynamos,  cen- 
trifugal pumps,  blowers,  etc.,  as  it  permits  the  use  of  small 
sizes  of  such  machines,  the  high  speed  is  a  disadvantage  in  the 
majority  of  cases.  But  there  is  another  serious  obstacle  to  the 
high  speed,  viz.,  the  limited  strength  of  the  material  of  which 
the  runner  is  made.  For  example,  with  150  Ibs.  gage  pressure 
and  28  ins.  vacuum,  steam  would  flow  out  of  an  expanding  nozzle 
with  a  velocity  of  nearly  4000  ft.  per  second,  and  to  utilize  this 
speed  in  a  single-stage  action  turbine,  such  as  the  De  Laval,  would, 
require  a  rim  speed  of  about  1800  ft.  per  second,  which  is  higher 
than  any  material  could  be  subjected  to  without  bursting.  To- 
reduce  the  speed  of  the  runner,  most  designers  employ  a  series, 
of  turbines,  utilizing  a  part  of  the  pressure  or  velocity  of  the  steam 
in  each  individual  turbine  or  stage  of  the  series. 

With  the  high  speeds  employed,  it  has  also  been  found  neces- 
sary to  permit  the  shaft  and  runner  to  revolve  about  their  axis 
of  gravity  instead  of  their  geometrical  axis,  to  allow  for  the  fact 
that  shaft  and  runner  may  be  out  of  balance,  due  to  lack  of  homo- 
geneity of  the  material  or  faulty  workmanship  or  both,  as  other- 
wise the  turbine  would  quickly  jar  itself  to  pieces. 

The  speed  regulation  of  steam-turbines  also  presents  some 
difficulties.  Most  turbines  are  now  regulated  by  some  device, 
which  throttles  the  steam  and  thus  causes  it  to  have  a  reduced! 


62  MODERN  TURBINE  PRACTICE. 

pressure  in  the  admission-chamber.  Like  with  hydraulic  tur- 
bines, it  is  more  difficult  to  regulate  reaction  steam-turbines  so 
as  to  show  good  efficiencies  at  part  load  than  action  steam-tur- 
bines. 

A  great  disadvantage  of  the  steam-turbine,  especially  for 
marine  work,  is  that  it  cannot  be  reversed,  except  by  having  a 
separate  set  of  guide-  and  runner-buckets  for  both  the  forward 
and  backward  motion. 

Steam-turbines  require  the  very  highest  class  of  material  and 
workmanship,  owing  both  to  their  high  speed  and  the  small  size 
and  large  number  of  their  parts.  A  400-H.P.  Westinghouse-Par- 
sons  steam-turbine,  for  example,  has  14,978  guide-vanes  and 
16,095  runner-vanes. 

It  may  be  well  to  mention  here  that  many  designs  of  gas- 
and  oil-turbines  have  been  proposed;  that  is,  turbines  in  which 
gas  or  oil  is  burned  with  air,  as  in  the  reciprocating  gas-  and  oil- 
engines. One  of  the  designs  was  brought  out  by  Mr.  De  Laval, 
but  he  has  since  abandoned  the  idea.  The  principal  difficulty  is 
that  the  air  required  for  combustion  has  to  be  compressed  by 
large,  slow-speed  reciprocating  air-compressors  with  their  adher- 
ent losses,  and  theoretical  investigations  have  shown  that  gas- 
and  oil-turbines  cannot  be  expected  to  show  a  greater  economy 
than  steam-turbines.1 

The  steam-turbines  built  in  the  United  States  at  present,  viz., 
the  Westinghouse-Parsons,  the  De  Laval,  the  Rateau,  and  the 
Curtis,  are  briefly  described  in  the  following: 

The  Westinghouse-Parsons  steam-turbine  shown  in  Fig.  11 
in  longitudinal  section  is  the  American  modification  of  the  Par- 
sons steam-turbine,  which  is  the  only  commercially  successful 
reaction  steam-turbine.2 

1  V.  Lorenc,  "  Waermeausnutzung  der  Heissluftturbinen,"  Zeitsch.  d.  V. 
deutsch.  Ing.,  Feb.  24,  1900,  p.  252. 

2  For  more  detailed  description  of  the  Westinghouse-Parsons  turbine,  see 
Francis  Hodgkinson,  "Steam  Turbines,"  in  proceedings  of   the  Engrs.  Soc. 
of  Western  Pennsylvania,  Nov.  1900;  also  "Some  Theoretical  and  Practical 
Considerations  in  Steam  Turbine  Work,"  read  before  the  Am.  Soc.  M.  E., 
June  2,  1904;  an  abstract  of  the  latter  printed  in  Engineering  News,  June  9, 
1904,  p.  553.     For  English  forms  of  Parsons  stationary  and  marine  turbines 
see  Stodola,  "Steam  Turbines,"  pp.  271,  311,  and  313. 


STEAM-TURBINES. 


63 


64  MODERN  TURBINE  PRACTICE. 

The  Westinghouse-Parsons  steam-turbine  is  a  series  turbine; 
that  is  to  say,  the  steam-pressure  is  utilized  in  a  number  of  axial 
turbines,  mounted  upon  the  same  shaft  and  each  forming  a  stage 
or  step  in  the  successive  expansions.  Being  a  reaction  turbine, 
the  steam-pressure  is  not  fully  converted  into  velocity  or  the 
steam  expanded  in  the  guide-buckets,  but  leaves  these  buckets 
still  under  pressure,  and  the  velocity  of  the  steam  is  further  increased 
and  its  volume  expanded  in  flowing  through  the  runner-buckets, 
which  absorb  the  velocity  and  kinetic  energy  of  the  steam,  and 
the  steam  issues  from  the  runner-buckets  with  the  proper  pres- 
sure for  entering  the  guide-buckets  of  the  next  turbine  or  stage. 
.As  the  steam  leaves  the  guide-buckets  still  under  pressure,  there 
will  of  course  be  a  certain  amount  of  leakage  through  the  clear- 
ance between  guide-  and  runner-buckets  and  around  the  runner- 
~to  the  guide-buckets  of  the  next  stage. 

The  steam  enters  the  turbine  through  the  admission-chamber  A 
in  Fig.  11,  and  flows  to  the  right  through  the  successive  stages 
•of  guide-  and  runner-buckets,  the  passage  areas  of  these  buckets 
increasing  as  the  volume  of  the  steam  increases  by  expansion. 
.After  a  number  of  turbines  have  been  passed,  it  becomes  necessary, 
in  order  to  further  increase  the  passage  areas  of  the  buckets,  to 
increase  the  diameter  of  the  set  of  turbines  following,  and  this 
increase  may  be  repeated  several  times,  as  shown  at  E  and  G, 
the  steam  finally  entering  the  exhaust-chamber  B. 

As  all  reaction  turbines  have  a  considerable  end  thrust,  special 
provisions  are  made  to  take  care  of  the  same.  For  this  purpose 
revolving  balance-pistons  C,  C,  and  C  are  provided,  which  corre- 
spond in  diameter  to  the  three  sets  of  turbines,  each  of  which  is 
subjected  to  the  same  pressure  as  exists  in  the  admission-chamber 
of  its  corresponding  set  of  turbines,  the  pistons  for  the  second 
;and  following  sets  being  connected  with  the  corresponding  admis- 
sion-chamber by  balance  ports,  as  shown  at  F  for  the  second  set. 
These  balance-pistons,  it  may  be  mentioned  here,  are  not  in  con- 
tact with  the  surrounding  cylinder,  and  while  this  will  cause  a 
certain  loss  by  leakage,  it  will  also  prevent  the  friction  loss,  except 
the  loss  due  to  the  friction  of  the  water  resulting  from  the  con- 
densation of  steam.  To  equalize  the  exhaust  pressure  with  the 
pressure  against  the  back  of  the  piston  corresponding  to  the  last 


STEAM-TURBINES.  65 

set  of  turbines,  the  pipe  connection  K  is  provided.  A  thrust- 
bearing,  shown  at  H,  is  provided  to  take  care  of  any  unbalanced 
end  thrust  and  thus  prevent  end  motion. 

By  means  of  the  by-pass  valve  P  and  the  port  Q,  the  full 
steam-pressure  in  the  first  admission-chamber  A  may  be  admitted 
to  the  second  admission-chamber  E,  to  provide  for  an  emergency 
overload  of  about  60%  and  to  permit  a  turbine  running  con- 
densing to  develop  its  full  power,  even  should  the  condenser  be 
inoperative  and  the  turbine  exhausting  into  the  atmosphere. 
The  opening  of  the  by-pass  naturally  reduces  the  economy  of 
the  turbine. 

The  heavy  turbine  shaft  with  its  runners  is  allowed  to  revolve 
abou€  the  axis  of  gravity,  by  the  peculiar  arrangement  of  the 
bearings  and  therefore  a  flexible  coupling,  shown  at  R,  becomes 
necessary  to  transmit  the  power  developed  by  the  turbine. 

The  lubricating  oil  drains  to  the  reservoir  N  and  the  pump  M 
raises  it  to  the  reservoir  0,  from  which  it  flows  to  the  rubbing 
surfaces  by  gravity. 

The  speed  regulation  of  the  Westinghouse-Parsons  turbine  is 
interesting,  as,  like  for  hydraulic  turbines,  a  relay  governor  is 
employed.  The  steam,  except  with  the  maximum  load,  does  not 
flow  continuously  into  the  admission-chamber  A,  but  enters  in 
consecutive  puffs,  the  duration  of  the  puffs  being  in  accordance 
with  the  load.  The  purpose  of  this  arrangement  is  to  always 
have  the  steam  enter  the  admission-chamber  with  the  full  initial 
pressure,  but  it  will  easily  be  seen  that  in  the  intervals  between 
puffs  the  pressure  in  the  admission-chamber  will  at  once  fall 
below  the  initial  pressure  and  that  the  pressure  in  the  second 
and  remaining  admission-chambers  will  be  little  different  from 
what  it  would  be  if  the  regulation  were  accomplished  by  simply 
throttling  the  steam. 

A  disadvantage  of  the  Westinghouse-Parsons  turbine  is  that 
owing  to  the  great  number  of  turbines,  the  small  clearances  necessary 
in  reaction  turbines,  and  the  fact  that  some  of  the  turbines  revolve 
in  a  high  steam-pressure,  there  will  be  a  comparatively  large  fric- 
tion loss,  which  will  be  much  increased  if  the  steam  is  not  super- 
heated and  thus  water  of  condensation  is  allowed  to  accumulate 
in  the  turbine. 


66 


MODERN  TURBINE  PRACTICE. 


The  De  Laval  steam-turbine  is  an  axial-flow  action  turbine 
with  partial  feed,  in  which  the  whole  steam-pressure  is  converted 
into  velocity  in  a  single  set  of  nozzles  and  this  velocity  and  kinetic 
energy  absorbed  by  a  single  runner.1 


FIG.   12  — Runner  and  Nozzles  of  De  Laval  Steam-turbine.     Built  by  the 
De  Laval  Steam  Turbine  Co.,  Trenton,  N.  J. 

The  pressure  of  steam  while  the  steam  is  flowing  through 
an  ordinary  nozzle  will  decrease  only  to  58%  of  the  absolute 

1  For  more  detailed  description  see  Stodola,  "Steam  Turbines,"  p.  216;  also 
Mr.  E.  S.  Lea's  paper,  "The  De  Laval  Steam  Turbine,"  read  before  the  Am. 
Soc.  M.  E.,  June  2, 1904,  and  printed  in  Engineering  News,  June  9, 1904,  p.  551. 


STEAM-TURBINES.  67 

initial  pressure,  and  in  order  that  the  whole  expansion  of  the  steam 
should  take  place  while  flowing  through  the  nozzle,  Mr.  De  Laval 
devised  the  expanding  or  diverging  nozzle  shown  in  Fig.  12.  The 
steam  in  flowing  through  the  throat  of  this  nozzle  expands  and 
decreases  in  pressure  to  58%  of  the  absolute  initial  pressure  and 
then  enters  and  flows  through  a  diverging  tube,  which  may  be 
considered  as  an  infinite  number  of  infinitely  short  nozzles  of 
successively  increasing  diameter,  in  each  of  which  the  steam 
expands  and  the  pressure  decreases,  so  that  with  a  nozzle  of  proper 
shape  and  length  the  steam  will  leave  the  discharge  end  of  the 
nozzle  with  a  pressure  equal  to  the  exhaust  pressure  and  con- 
taining the  whole  of  the  static  energy  of  the  steam  in  the  form 
of  kinetic  energy. 

The  steam  leaving  the  nozzles  at  exhaust  pressure,  there  will 
be  no  leakage  of  the  steam  between  the  nozzles  and  the  runner 
and  around  the  runner  to  the  exhaust  and,  as  the  runner  revolves 
in  the  exhaust  pressure,  the  friction  between  runner  and  steam 
will  be  reduced  to  a  minimum. 

The  principal  working  part  of  the  turbine  is  the  runner,  which 
is  shown  in  Fig.  12,  together  with  four  nozzles  in  their  proper 
positions.  For  best  efficiency  the  angle  of  actual  discharge  from 
the  runner-buckets,  marked  d  in  Fig.  10,  should  be  90°.  How- 
ever, this  is  impracticable  with  the  high  speed  of  the  steam  obtained 
with  a  diverging  nozzle,  which  may  reach  nearly  4000  ft.  per 
second,  as  the  rim  speed  would  be  too  high  and  in  practice  the 
angle  of  actual  discharge  is  therefore  made  considerably  smaller, 
thus  sacrificing  a  small  part  of  the  kinetic  energy.  The  initial 
and  terminal  angles  of  the  runner-vanes,  marked  ft  and  7-  in  Fig.  10, 
are  made  the  same  and  the  end  thrust  is  therefore  eliminated. 

The  runner-disk  increases  in  thickness  from  the  outer  rim 
towards  the  center,  as  by  this  form  a  much  greater  resistance 
against  bursting  is  obtained. 

The  runner-shaft  is  very  thin,  and  by  deflecting  will  allow  the 
runner  to  revolve  about  its  axis  of  gravity.  The  high  rotative 
speed  of  the  runner,  which  varies  between  10,000  revolutions  for 
the  larger  sizes  and  30,000  revolutions  per  minute  for  the  smaller 
sizes  of  turbines,  is  reduced  by  means  of  double  helical  spur-gears, 
shown  at  J  and  K  in  Fig.  13,  the  reduction  being  about  10  to  1. 


68 


MODERN  TURBINE  PRACTICE 


STEAM-TURBINES.  69 

The  gears,  or  for  the  larger  sizes  the  gear-rims,  are  of  cast  steel 
with  very  fine  cut  teeth.  The  helical  form  of  the  teeth  not  only 
insures  smooth  running,  but  also  prevents  end  motion  of  the 
runner-shaft. 

The  governor  of  the  De  Laval  turbine  effects  the  speed  regu- 
lation by  the  throttling  of  the  steam,  which  of  course  somewhat 
reduces  the  efficiency  at  part  loads.  However,  each  nozzle  is 
provided  with  a  separate  stop-valve  operated  by  hand,  so  that 
when  running  with,  say,  one  half  of  the  maximum  load  and  closing 
one  half  of  the  number  of  nozzles,  the  turbine  will  show  practi- 
cally the  full-load  efficiency. 

The  Rateau  steam-turbine  is  essentially  a  series  of  action 
turbines  of  the  De  Laval  type,  all  the  runners  being  mounted  upon 
the  same  shaft,  like  those  of  the  Westinghouse-Parsons  turbine.1 
Each  runner  revolves  in  a  compartment  by  itself,  the  compart- 
ments being  separated  from  each  other  by  stationary  disks,  each 
compartment  with  its  runner  forming  a  stage  in  the  expansion  of 
the  steam,  thus  reducing  the  discharge  velocity  of  the  steam  for 
each  individual  stage. 

Instead  of  the  nozzles  of  the  De  Laval  turbine,  guide-buckets 
arranged  in  groups  are  used,  which  effect  the  passage  of  the 
steam  through  the  stationary  disks. 

Mr.  Rateau  has  also  constructed  a  successful  impulse  steam- 
turbine  with  buckets  of  the  Pelton  type. 

The  Curtis  steam-turbine  is  an  action  turbine  with  axiai  flow 
and  partial  feed,  having  a  number  of  runners  mounted  upon  the 
same  shaft,  which  shaft  is  usually  arranged  vertically  and  carried 
by  an  oil  step-bearing,  that  is,  floating  on  oil  under  pressure.2 

The  steam  is  expanded  in  two  or  more  stages.  The  guide- 
buckets  or  nozzles  are  diverging,  as  shown  in  Fig.  14,  and  for 


1  For  more  detailed  description  see  Stodola,  "Steam  Turbines,"  p.  258; 
also  Prof.  A.  Rateau's  paper,  "Different  Applications  of  Steam  Turbines,' 
read  before  the  Am.  Soc.  M.  E.,  June  2,  1904,  and  printed  in  abstract    in 
Engineering  News,  June  9,  1904,  p.  544. 

2  See  Stodola,  "  Steam  Turbines,"  p.   246;  also  Mr.  W.  L.  R.  Emmet's 
paper,  "The  Steam  Turbine  in  Modern  Engineering,"  read  before  the  Am. 
Soc.  M.  E.,  June  2,  1904,  and  printed  in  abstract  in  Engineering  News,  June 
9,  1904,  p.  552. 


70 


MODERN  TURBINE  PRACTICE. 


the  first  stage  are  arranged  in  one  to  three  groups,  but  for  the 
following  stages  they  may  extend  around  the  whole  periphery. 
The  velocity  and  kinetic  energy  of  the  steam  leaving  the  guide- 
buckets  is  not  absorbed  by  a  single  runner,  but  a  part  of  it  by 
each  of  the  three  or  more  runners  in  each  stage,  thus  permitting 

STEAM  CHEST 


NOZZLE 
MOVING    BLADES 
STATIONARY  BLADES 
MOVING     BLADES 
STATIONARY  BLADES 
MOVING    BLADES 


'ZLE  DIAPHRAGM 


MOVING  BLADES 


STATIONARY 
BLADES 


MOVING  BLADES 


STATIONARY 
BLADES 


MOVING  BLADES, 


FIG.  14. — Diagram  of  Curtis  Steam-turbine,  Showing  Nozzles,  Runner- 
buckets,  and  Deflecting-vanes  for  First  and  Second  Stage.  Built  by 
the  General  Electric  Co.,  Schenectady,  N.  Y. 

the  use  of  a  lower  rim  speed  for  the  runners.  Between  each  pair 
of  runners  deflecting-vanes  are  located,  to  redirect  the  steam 
before  entering  the  next  runner,  as  shown  in  Fig.  14.  After  the 
steam  has  passed  all  the  runners  of  a  stage  and  all  the  kinetic 
energy  has  been  absorbed,  the  steam  enters  the  next  set  of  diverg- 


STEAM-TURBINES.  7 1 

ing  guide-buckets  or  nozzles  located  in  the  nozzle  diaphragm, 
which  is  a  stationary  disk  forming  the  division  wall  between 
the  successive  stages. 

The  initial  and  terminal  angles  of  the  runner-vanes,  marked  ft 
and  7-  in  Fig.  10,  are  made  the  same  and  the  end  thrust  is  there- 
fore eliminated. 

With  a  two-stage  turbine,  built  to  run  condensing,  only  the 
first  stage  is  used,  when  the  turbine  is  exhausting  against  the 
atmosphere. 

The  speed  regulation  of  the  Curtis  turbine  is  effected  by  a 
relay  governor,  which  operates  the  valves  controlling  the  flow 
of  steam  from  the  admission-chamber  or  steam-chest  to  the  guide- 
buckets  of  the  first  stage,  opening  or  closing  them  one  after  an- 
other, as  may  be  required.  If  desired,  the  steam  admission  to 
the  following  stages  can  also  be  regulated. 

The  working  principles  of  the  steam-turbines  here  described 
may  briefly  be  stated  as  follows: 

Westinghouse-Parsons  series  reaction  turbine:  The  steam  ex- 
pands both  in  the  guide-  and  runner-buckets.  The  velocity  and 
kinetic  energy  resulting  from  the  expansion  in  each  individual 
stage  are  absorbed  by  a  single  runner  in  each  stage. 

De  Laval  single-action  turbine:  The  steam  is  fully  expanded 
in  a  single  set  of  guide-buckets  or  nozzles  and  the  resulting  velocity 
and  kinetic  energy  are  absorbed  by  a  single  runner. 

Rateau  series  action  turbine :  The  steam  expands  in  the  guide- 
buckets  only.  The  velocity  and  kinetic  energy  resulting  from 
the  expansion  in  each  individual  stage  are  absorbed  by  a  single 
runner  in  each  stage. 

Curtis  series  action  turbine:  The  steam  expands  in  the  guide- 
buckets  only.  The  velocity  and  kinetic  energy  resulting  from 
the  expansion  in  each  individual  stage  are  absorbed  by  a 
number  of  runners  with  intervening  deflecting  vanes  in  each 
stage. 

The  following  table l  gives  a  comparison  of  the  steam-turbines 


1  From  Mr.  Austin  R.  Dodge's  paper,  "Advantages  of  Steam  Turbines  for 
Textile  Mills,"  read  before  the  New  England  Cotton  Manufacturers'  Assoc., 
1903;  also  an  abstract  in  Engineering  News,  Oct.  22,  1903,  p.  359. 


UNIVERSITY  OF  CALIFORNIA 


72 


MODERN  TURBINE  PRACTICE. 


above  described.    The  velocities  given  are  for  turbines  of  300  to 
600  H.P.  and  are  approximate  only. 


Type. 

Number 
of 
Runners. 

Steam 
Velocity, 
Feet  per 
Second. 

Revolu- 
tions 
per 
Minute. 

Rim, 
Speed. 

Buckets. 

Westinghouse  -Parsons 

35 

400 

3  600 

200 

inserted. 

1 

4000 

20  000 

1200 

inserted 

Rateau      

25 

800 

2  400 

400 

inserted^ 

8 

2000 

1  800 

400 

solid 

CHAPTER  V. 
MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION. 

Turbine  Construction  in  General.— Taking  into  consideration- 
all  the  faults  of  the  present  turbine  practice,  the  increased  use  of 
turbines  in  general,  and  of  turbines  for  driving  dynamo  machines- 
in  particular,  the  necessity  of  radical  improvements  will  be  appar- 
ent. The  writer  would  therefore  suggest  that  turbines  should 
be  designed  and  built  with  the  same  care  that  is  given  to  other 
high-grade  machinery,  and  further,  that  three  distinct  types  of 
turbines  be  adopted.  The  type  to  be  employed  in  each  individual 
case  should  be  in  accordance  with  the  height  of  the  head  to  be 
utilized  as  follows: 

1.  Low  heads,  say  up  to  40  ft.:    American  type  of  turbine 
with  horizontal  or  vertical  shaft  in  open  flume  or  case,  nearly 
always  with  draft-tube. 

2.  Medium  heads,  say  from  40  to  300  or  400  ft. :  Radial  inward- 
flow  reaction   turbine  with  horizontal  shaft   and   concentric   or 
spiral  cast-iron  case  with  draft-tube. 

3.  High  heads,  say  above  300  or  400  ft.  :t  Impulse  turbine  or 
radial  outward-flow  full  or  partial  action  turbine,  or  a  combina- 
tion of  both  with  horizontal  shaft  and  cast-  or  wrought-iron  case, 
often  with  draft-tube. 

Extremes  in  speed  or  power  or  both  will,  of  course,  often 
demand  the  use  of  a  turbine  type  for  a  head,  outside  of  the  range 
for  which  the  type  is  here  proposed. 

Turbines  with  horizontal  shafts  should  be  employed  in  all 
cases,  except  where  the  use  of  turbines  with  vertical  shafts  is 
either  imperative  or  gives  a  decided  advantage  over  turbines 
on  horizontal  shafts.  Horizontal  turbines  are  not  only  more 
convenient  in  attendance  and  easier  of  access  for  adjustment  or 

73 


74  MODERN  TURBINE  PRACTICE. 

repairs,  but  most  of  the  transmission  of  power  is  done  by  hori- 
zontal shafts  and  nearly  all  standard  patterns  of  direct-driven 
dynamos  or  other  machinery  are  arranged  to  connect  to  a  hori- 
zontal driving-shaft.  With  a  very  low  total  head  or  pressure- 
head  above  the  turbine,  it  will  often  be  necessary  to  use  vertical 
turbines  to  be  able  to  utilize  such  a  head  at  all.  In  many  loca- 
tions horizontal  turbines,  on  account  of  the  great  rise  of  the  tail- 
water  during  times  of  flood,  would  have  to  be  set  at  so  great  a 
height  above  low  tailwater  that  the  head  below  the  turbine 
would  be  utterly  beyond  the  practical  working  limit  of  a  draft- 
tube  during  the  low-water  season  and  part  of  the  head  would 
thus  have  to  be  sacrificed  just  at  the  time  of  least  water.  In 
such  a  case  vertical  turbines  are  of  great  advantage,  as  they  may 
be  set  at  any  elevation,  because  their  being  submerged  during 
times  of  flood  does  not  interfere  with  their  operation. 

The  mechanical  or  friction  losses  in  vertical  turbines,  arranged 
to  carry  the  revolving  parts  on  the  water  or  by  water  thrust,  are 
less  than  in  horizontal  turbines. 

Cast-iron  or  steel  turbine  cases  and  draft-tubes  may  in  most 
instances  be  dispensed  with  in  connection  with  vertical  turbines 
by  making  the  concrete  of  the  power-house  foundations  form 
the  case  and  draft-tube.  (See  Figs.  19  and  21.) 

The  use  of  dynamos  with  vertical  shafts  direct  connected  to 
vertical  turbines  gives  an  excellent,  compact,  and  neat  arrange- 
ment, as  shown  by  the  large  plants  of  the  Niagara  Falls  Power  Co., 
the  German  plant  at  Rheinfelden,  the  Swiss  plants  at  Neuhausen, 
Beznau  (Fig.  19),  Chevres  (Fig.  21),  the  French  plant  at  Lyons 
(Fig.  20),  and  many  others. 

This  arrangement  was  also  proposed  by  the  writer  for  the 
development  at  Shawinigan  Falls,  Que.,  and  it  is  to  be  regretted 
that  it  was  not  adopted,  as  may  easily  be  seen  by  comparing 
the  writer's  proposed  plan  shown  in  Figs.  15  and  16  with  the 
plan  actually  carried  out,  shown  in  Figs.  17  and  18.1 

Dynamos  with  vertical  shafts,  having  to  be  built  specially, 
will  cost  more  than  standard  machines,  but  if  specially  designed 


1  The  horizontal  turbines  installed  at  this  plant  are  shown  in  Figs.  57 
and  58. 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.      75 

and  built  dynamos  are  to  be  used  in  any  case,  the  dynamos  with 
vertical  shaft  will  cost  about  the  same  or  less  than  machines  with 
horizontal  shaft  of  the  same  capacity -and  number  of  revolu- 
tions. 

Centrifugal  pumps  with  vertical  shafts  and  piston-pumps  and 
compressors  with  vertical  crank-shafts  are  also  built  occasionally 
to  permit  direct  connection  with  vertical  turbines  where  con- 
ditions make  the  employment  of  the  latter  imperative.  (See 
Figs.  1  and  2.) 

To  transmit  the  power  of  turbines  by  gears  should  always 
be  avoided,  especially  the  common  plan  of  driving  a  horizontal 
shaft  from  a  vertical  turbine  by  bevel-gears. 

This  arrangement  is  now  much  used  in  connection  with  very 
low  heads  where  one  or  more  vertical  slow-speed  turbines  drive 
a  horizontal  shaft  which  runs,  as  a  rule,  at  a  much  higher  speed 
and  is  often  direct  connected  to  a  dynamo  or  other  machine. 
European  engineers  prefer  direct  connection  of  dynamos  even  if 
the  dynamos  have  to  be  much  larger  and  more  expensive.  Thus 
the  power-plant  at  Rheinfelden,  Germany,  utilizing  a  head  of 
from  10.5  to  14.75  ft.,  contains  twenty  direct-connected  vertical 
units  of  840  H.P.  each.  Nine  of  these  units,  comprising  the  first 
installation,  make  55  revolutions  per  minute,  while  the  remain- 
Ing  11  units,  using  a  later  type  of  turbines,  run  at  68  revolutions. 
Another  slow-speed  power-plant  is  the  one  at  Beznau,  Switzer- 
land (Fig.  19),  utilizing  a  head  of  12.8  to  18.7  ft.  and  containing 
11  direct-connected  vertical  units  of  1000  H.P.  each,  running 
;at  66f  revolutions. 

The  American  engineer  does  not  look  favorably  at  slow-moving 
machines,  especially  if  these  machines  are  dynamos,  on  account 
of  their  greater  cost,  but  on  the  other  hand  a  slow-moving  machine 
has  a  far  longer  life  than  a  fast-moving  one,  and  for  direct-con- 
nected dynamos  an  increased  speed  means  smaller  turbine  diam- 
eters and  an  increased  number  of  turbines  to  each  unit,  therefore 
a  greater  cost  of  a  turbine  installation  for  the  same  capacity. 

In  general  it  may  be  said  that  turbines,  both  those  on  hori- 
zontal and  on  vertical  shafts,  should  be  self-contained;  that  is, 
all  stationary  parts  should  be  securely  connected  to  one  rigid 
main  frame  or  base,  or  to  such  main  parts  of  the  turbine  as  are 


76 


MODERN  TURBINE  PRACTICE. 


FIG.  16. 

FIGS.  15  and  16. — Proposed  Vertical  Arrangement  of  Turbines  for  the  Power- 
house of  the  Shawinigan  Water  and  Power  Co.,  Shawinigan  Falls,  Que. 
Area  occupied    by  power-house:    Horizontal,    18,400  sq.   ft.;    vertical, 
7840  sq.  ft. 

Increased  cost  of  horizontal  over  vertical  arrangement : 

On  excavation,  at  $1  per  cubic  yard $9,740 

11   concrete  and  floors,  at  $8  per  cubic  yard 40,000 

"   penstocks,  at  $55  per  running  foot 10,000 

"  building,  brick,  roof,  windows,  and  heating-plant. .        5,420 

$65,160 


MODERN  TURBINE  TYPES    AND  THEIR  CONSTRUCTION.     77 

#yt,  MM/  nW«-.  i9r-» 


PIG.  18, 

FIGS.  17  and  18. — Horizontal  Arrangement  of  Turbines  for  the  Power-house 
of  the  Shawinigan  Water  Power  Co,  Shawinigan  Falls,  Que.,  as 
Actually  Installed.  Designed  bv  W  C.  Johnson.  C.E..  Montreal.  Oue 


78  MODERN  TURBINE  PRACTICE. 

arranged  to  serve  as  a  frame  or  base,  but  a  turbine  case  of  iron 
or  steel  plate  should  never  be  employed  as  a  frame. 

Main  frames  or  bases  should  be  used  in  all  cases,  even  where 
the  turbine  rests  on  solid  masonry  or  concrete  work,  and  they 
should  be  constructed  of  cast  iron  in  preference  to  wrought  iron 
or  wrought  steel,  as  cast  iron  is  more  rigid  than  the  wrought  metal. 
The  shape  of  the  frame  will  vary  according  to  the  general  arrange- 
ment of  the  turbines,  but  a  form  of  box  girder  with  deep  webs, 
well-stiffened  sideways,  and  with  wide  flanges  will  answer  in  most 
'cases.  The  joints  between  the  frame  parts  themselves  and  between 
.the  frame  and  the  turbines  should  be  planed. 

Turbine  frames  should  never  be  made  to  serve  as  beams,  and 
•where  turbine-pits  or  tailraces  are  directly  below  the  turbines, 
masonry  arches  or  concrete  and  steel  contruction  should  be  employed 
to  bridge  over  these  openings  and  to  support  the  turbine-frames. 

Where  turbine-shafts  are  direct  connected  to  the  shaft  of 
'dynamos  or  other  machinery,  it  is  advisable  to  have  the  main 
frames  of  the  turbines  extended  or  separate  connecting  pieces 
provided,  so  that  the  frames  of  the  turbines  and  those  of  the 
-dynamos  or  other  machinery  may  be  bolted  together  rigidly, 
Tthus  making  the  alinement  and  proper  working  of  the  connected 
^machines  independent  of  careless  and  faulty  erection  and  unequal 
:settlement. 

Turbine-cases  should  be  of  such  shape  that  all  changes  in 
:speed  and  direction  of  the  water  are  made  gradually.  Water, 
on  account  of  its  inertia,  cannot  change  its  speed  instantly,  and 
therefore  any  sudden  change  in  the  clear  area  of  a  water  con- 
ductor will  form  a  pocket  in  which  part  of  the  main  flow  of  the 
"water  is  detained  and  whirled  around. 

All  turbine-cases  should  be  provided  with  proper  drain-valves 
to  empty  them  of  water  or  to  flush  out  stones,  sand,  etc. 

To  admit  the  water  to  the  turbine-case  at  the  end  or  in  an 
axial  direction  should  be  avoided,  as  this  arrangement  implies 
that  one  of  the  main  shaft-bearings  is  to  be  located  in  the  water. 
With  turbines  set  in  an  open  chamber,  it  can  rarely  be  avoided 
to  have  one  of  the  main  bearings  under  water. 

Where  circumstances  will  permit,  a  case  with  end  inlet  similar 
to  the  type  shown  in  Fig.  35  may  be  used,  which  could  easily 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.     79s 

be  modified  so  as  to  have  both  main  bearings  outside  of  the 
case. 

Except  where  required  to  carry  the  weight  of  the  revolving 
parts,  it  is  to  be  avoided  to  have  the  full  head  or  water  pressure 
acting  against  the  runner-disk  of  reaction  turbines.  The  pressure 
against  the  disk,  due  to  the  leakage  from  the  clearance,  cannot 
be  avoided,  but  may  generally  be  relieved  and  the  end  thrust 
thus  reduced  by  having  openings  in  the  runner-disk  connecting 
the  space  between  the  disk  and  the  head  of  the  case  or  the  gate 
dome  with  the  discharge  side  of  the  turbine.  (See  Figs.  25,  26, 
29,  30,  34,  and  35.) 

The  American  type  of  runner,  being  a  very  difficult  piece  to 
mold,  is  now  often  built  up  from  separate  pieces,  each  piece  form- 
ing one  or  more  buckets,  but  such  built-up  runners  are  only  per- 
missible if  they  are  very  carefully  made  and  strongly  banded. 

Manufacturers  making  the  runners  of  the  American  type  in  one 
casting  frequently  use  a  very  soft  cast  iron,  as  such  iron  when 
molten  is  more  fluid  and  better  fills  the  molds  than  the  harder 
metal.  This  means  a  rapid  wear  of  the  buckets,  due  to  the  erosion 
caused  by  the  sand  and  gritty  matter  carried  by  the  water.  The 
writer  has  in  mind  an  instance  where  48-in.  turbines,  working 
under  a  head  of  only  28  ft.,  wore  so  rapidly  that  after  three  years 
of  operation  nothing  remained  of  some  of  the  runners  but  the 
hubs  and  small  fragments  of  the  buckets. 

As  the  erosion  may  be  taken  to  increase  directly  with  the 
head  or  with  the  square  of  the  velocity  of  the  water,  it  will  be 
evident  that  for  high  heads,  especially  as  mostly  action  turbines 
are  used  in  connection  with  them,  the  buckets  should  be  of  a 
hard  cast-iron,  steel  casting,  manganese,  or  phosphor-bronze  to 
reduce  the  wear  to  a  minimum.  Of  course,  with  high  heads  and 
small  volumes  of  water,  that  is  with  small  rates  of  flow,  much 
better  precautions  can  be  and  are  usually  taken  to  free  the  water 
from  sand  and  gritty  matter  than  is  the  case  with  low  heads 
and  large  volumes  of  water. 

To  free  large  volumes  of  water  from  sand  and  gritty  matter 
is  often  very  difficult  and  expensive,  and  in  such  instances  it  will 
be  found  cheaper,  as  a  rule,  not  to  attempt  it,  but  to  renew  guide- 
and  runner-buckets  when  worn  out.  Except  for  turbines  of  very 


CIVIL  ENGINEEI. 


80  MODERN  TURBINE  PRACTICE. 

small  diameter,  the  guide-  and  runner-vanes  with  their  crowns 
should  therefore  be  cast  as  separate  rings,  to  be  bolted  to  the 
turbine-case  and  the  runner-disk  respectively,  as  this  will  greatly 
lessen  the  cost  of  renewal,  besides  making  these  parts  somewhat 
easier  to  mold.  The  threads  of  the  bolts  used  for  this  purpose 
should  be  coated  with  red  lead  or  graphite  to  prevent  the  nuts 
from  rusting  fast. 

Corrosion  of  iron  is  caused  by  the  combined  action  of  moisture 
and  the  carbonic  acid  in  the  atmosphere.  There  is  little  trouble 
with  corrosion  of  the  buckets  of  reaction  turbines  which  work 
continuously  or  are  always  submerged,  but  the  backs  of  the  runner- 
vanes  of  action  turbines  with  free  deviation  and  of  the  buckets 
of  impulse  turbines  will  often  corrode  and  pit  very  quickly,  as  they 
are  always  in  contact  with  the  air  and  continually  wetted  by 
splashing  water,  thus  presenting  the  most  favorable  conditions 
for  rapid  corrosion. 

European  builders  therefore  now  frequently  make  the  runner- 
buckets  of  action  and  impulse  turbines  working  under  high  heads 
of  manganese  bronze,  as  this  material  not  only  offers  great  resist- 
ance to  corrosion  and  erosion,  but  also  has  a  great  strength,  its 
ultimate  tensile  strength  varying  between  45,000  to  60,000  Ibs. 
per  sq.  in.  for  the  cast  metal,  with  an  elongation  of  8  to  12%. 
Phosphor-bronze  having  an  ultimate  tensile  strength  of  from 
44,000  to  52,000  Ibs.  per  sq.  in.  and  an  elongation  of  8  to  33%, 
is  also  often  used  for  this  purpose. 

Should  a  governor  regulating  the  speed  of  a  turbine  fail  to 
act  while  the  turbine  is  running  without  a  load,  the  speed  of  the 
turbine  may  increase  to  almost  twice  the  normal  speed,  and  the 
runner  should  for  this  reason  be  capable  of  withstanding  twice 
the  normal  speed  without  being  in  immediate  danger  of  bursting. 

The  end  thrust  in  a  plain  inflow  reaction  turbine  is  principally 
due  to  the  water-pressure  between  the  head  of  the  case  or  the 
dome  and  the  runner-disk.  To  this  has  to  be  added  for  tur- 
bines in  which  the  direction  of  the  water  is  changed  from  the 
radial  inward  to  the  axial  direction,  while  flowing  through  the 
runner-buckets,  as  in  the  vortex  turbine,  the  axial  water-pressure 
against  the  discharge  end  of  the  runner-vanes,  for  it  is  this  part 
of  the  vanes  which  deflects  the  water  from  a  more  or  less  axial 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.     81 

direction  to  the  realtive  direction  of  discharge  denoted  by  ct  in 
Fig.  10.  Opposed  to  the  end  thrust  is  the  pressure,  due  to  the 
deflection  of  the  water,  from  the  inward  to  the  axial  direction 
while  flowing  through  the  runner-buckets. 

End-thrust  bearings  with  wooden  steps  should  be  abandoned 
and  metal  steps,  or,  better  still,  metal  collar  thrust-bearings, 
used  instead.  Such  metal  thrust-bearings  should,  of  course, 
never  be  located  in  the  water,  but  are  usually  placed  on  the  end 
of  the  shaft,  opposite  to  the  end  from  which  the  power  of  the 
turbine  is  taken  off.  Both  the  straight  and  the  collar  bearings 
of  the  main  turbine-shaft  should  be  adjustable,  and  should  be 
lined  with  bronze  as  a  base,  and  the  bronze  in  turn  lined  with  an 
anti-friction  metal  or  babbitt  well-hammered  and  bored. 

For  turbines  having  a  great  end  thrust,  such  as  single  tur- 
bines working  under  a  head  of  several  hundred  feet,  the  thrust- 
chamber  should  be  employed.  Turbines  having  runners  of  such 
size  or  shape  as  to  prevent  the  use  of  a  thrust-chamber,  as  the 
American  or  vortex  turbine  for  example,  should  employ  the  thrust- 
piston  instead,  placing  the  runner  at  one  end  and  the  piston  at 
the  other  end  of  the  case. 

No  packing  is  used  for  a  thrust-piston,  but  the  piston  closely 
fits  the  cylinder,  and  grooves  are  turned  in  the  piston,  as  shown 
in  Fig.  5,  to  reduce  the  leakage  of  water. 

If  the  water  used  for  a  turbine  contains  much  sand  or  gritty 
matter,  a  separate  water-supply  should  be  provided  for  the  thrust- 
piston,  and  this  water  should  be  run  through  a  sand-settler  or  a 
filter  or  screen,  to  free  it  from  the  sand  or  gritty  matter,  as  other- 
wise the  thrust-piston  will  wear  rapidly. 

Turbines  having  a  thrust  chamber  or  piston  or  double  tur- 
bines in  which  the  two  end  thrusts  balance  each  other,  always 
require  in  addition  a  small  collar-bearing,  to  take  care  of  unavoid- 
able variations  in  the  end  thrust. 

Cylinder  gates  are  the  simplest  form  of  gate  arrangement, 
but  their  use  considerably  increases  the  axial  dimension  of  the 
whole  turbine,  and  the  distance  between  main  bearings  has  to 
be  much  greater  than  is  required  with  register  or  wicket  gates. 

To  have  bolts,  nuts,  lugs,  or  other  projections  in  the  water- 
passages  of  the  guide-buckets,  as  now  frequently  found  in  con- 


82  MODERN  TURBINE  PRACTICE. 

nection  with  wicket  gates,  is  strongly  to  be  condemned,  as  such 
bolts,  nuts,  or  lugs  prevent  the  smooth  flow  of  the  water  and  pro- 
duce friction  and  eddies,  thus  greatly  reducing  the  efficiency. 

By  using  register  or  wicket  gates  for  double  turbines  the 
center  bearing  may  be  dispensed  with. 

All  outside  journal-bearings  should  be  self-oiling,  such  as  ring 
or  chain  oiling  bearings. 

For  all  journals  located  under  water,  for  which  wooden  bear- 
ings are  now  employed,  metallic  bearings  should  be  used  provided 
with  forced  oil  circulation,  as  shown  in  Fig.  25. 

Such  oil  circulation  has  also  the  advantage  that  the  oil  return- 
ing from  the  bearings  will  show  whether  any  cutting  takes  place 
in  the  bearings. 

The  oil  force-pumps  should  always  be  installed  hi  duplicate, 
so  that  the  breaking  down  of  an  oil-pump  will  not  necessitate 
the  stopping  of  the  whole  plant. 

The  body  of  the  stuffing-boxes  for  the  main  shaft  should  be 
separate  from  the  heads  of  the  turbine-case  and  bolted  to  the 
heads,  so  that  by  loosening  these  bolts  their  centers  may  be 
slightly  shifted.  This  will  permit  the  runner  to  be  accurately 
centered  with  the  guide-ring  and  the  main  bearings  to  be  properly 
adjusted,  moving  the  stuffing-boxes  with  the  shaft  as  required. 
Such  a  shifting  arrangement  for  the  stuffing-boxes  is  of  great 
importance  in  connection  with  turbine-cases  made  of  steel  plate, 
as  these  cases  are  likely  to  spring  or  warp  considerably. 

The  mechanism  for  actuating  the  gates  should  always  be  out- 
side the  turbine  case  or  flume  and  connected  to  the  gates  them- 
selves by  rods,  entering  the  case  or  flume  through  stuffing-boxes. 
Gears  for  moving  the  gates  should  be  avoided,  and  levers,  links, 
or  hydraulic  pistons,  or  a  combination  of  these,  used  instead. 

To  have  everything,  even  the  gate  domes  and  draft-tube  tees, 
inside  a  large  and  all-surrounding  case,  as  is  now  the  general  prac- 
tice for  the  sake  of  cheapness,  is  not  only  unnecessary  but  must 
be  regarded  as  an  unmitigated  nuisance. 

Most  gates  have  a  strong  tendency  either  to  close  or  to  open, 
according  to  their  arrangement,  and  this  force  always  tending 
to  move  the  gates  in  one  direction  should  be  counterbalanced, 
especially  when  a  governor  is  employed  for  regulating  the  gate 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.     83 

movement.  However,  this  balancing  should  not  be  done  by 
counterweights  and  chains,  but  by  the  pressure  of  the  power- 
water,  applied  to  parts  of  the  gates  provided  for  that  purpose- 
or  to  balancing-pistons.  Besides  doing  away  with  weight,  chains, 
and  their  rigging,  such  an  arrangement  has  the  advantage  that 
any  variation  in  head  which  increases  or  decreases  the  tendency 
of  the  gate  to  move  also  changes  the  balancing  pressure  in  the 
same  proportion.  Where  a  long  penstock  is  used  to  supply  tur- 
bines having  gates  with  a  tendency  to  close,  as  is  the  case  with 
nearly  all  gates,  it  is  advisable  to  have  these  gates  provided  with 
dashpots  to  prevent  them  from  moving  too  rapidly,  as  otherwise 
the  penstock  may  be  wrecked  should  any  part  of  the  gate  rigging 
give  way  and  the  gates  thus  be  permitted  to  close  suddenly. 

The  turbine-governor  should  be  regarded  as  an  essential  part 
of  the  turbine,  and  for  horizontal  turbines  at  least  the  governor 
should  be  mounted  either  on  the  turbine  frame  or  on  the  case.  The 
governor-drive  should  be  positive,  that  is  by  shafts  and  gears  in 
preference  to  a  belt.  The  gears  used  for  the  governor-drive  and 
such  gears  as  may  be  found  in  the  governor  itself  should  be  the 
only  gears  employed  about  a  turbine  unit. 

The  careful  design  of  turbines,  mentioned  above  as  necessary, 
includes,  of  course,  easy  access  to  every  part  and  at  all  stages  of 
the  water. 

Proper  manholes  should  therefore  be  provided  and  shafts, 
runners,  and  guide-rings  arranged,  so  that  they  may  be  easily 
removed  without  dismantling  the  whole  turbine. 

All  anchor-bolts  and  similar  parts  should  be  arranged  to  per- 
mit of  easy  renewal.  Bolt- threads  should  not  be  located  in 
damp  or  wet  places,  but  where  this  cannot  be  avoided,  the  threads 
should  be  coated  with  red  lead  or  graphite  to  prevent  the  nuts 
from  rusting  fast,  and  after  the  nuts  have  been  tightened,  the 
bolt  ends,  nuts,  and  washers  should  receive  a  thick  coat  of 
asphaltum,  to  exclude  the  moisture. 

Turbines  for  Low  Heads. — For  low  heads  the  writer  considers 
the  American  turbine  as  the  best  type,  and  would  recommend 
that  the  turbines  be  set  above  tailwater  and  supplied  with  draft- 
tubes  in  all  cases  where  the  head  is  sufficient  to  give  enough  depth 
of  water  above  the  turbine,  so  that  the  buckets  will  always  be 


84  MODERN  TURBINE  PRACTICE. 

properly  filled  and  the  air  prevented  from  being  sucked  through. 

Where  a  sufficient  depth  of  water  above  the  guide-buckets 
cannot  be  secured  or  other  reasons  make  it  advisable  to  install 
vertical  turbines,  it  has  been  the  univerasl  practice  in  America 
to  use  single  vertical  turbines,  and  as  such  turbines  under  the 
low  heads  for  which  they  are  employed  give,  as  a  rule,  too  low  a 
speed  if  of  the  proper  horse-power,  or  too  low  a  horse-power  if 
running  at  the  proper  speed,  the  gearing  of  one  or  more  vertical 
turbines  to  a  horizontal  shaft  becomes  necessary. 

As  far  as  the  writer  is  aware,  multiple  turbines  on  vertical 
shafts  and  working  under  low  heads  have  never  been  used  in 
American  plants  of  any  importance,  while  they  are  very  common 
in  European  practice.  The  turbines  in  the  power-house  No.  1 
of  the  Niagara  Falls  Power  Co.  are  double  turbines  on  vertical 
shafts,  but  they  are  working  under  a  mean  head  of  138  ft. 

However,  the  vertical  multiple  turbine  is  deserving  of  a  more 
general  application  for  low  heads,  and  as  their  arrangement  is 
practically  unknown  to  most  American  engineers,  a  number  of 
typical  plants  will  here  be  illustrated,  but  it  may  be  stated  first, 
as  pertaining  to  all  such  plants,  that  vertical  turbine  units  which 
are  continually  or  at  times  of  flood-water  partly  or  wholly  sub- 
merged must  each  be  placed  hi  an  independent  tailrace.  Each 
tailrace  has  to  be  provided  with  slides  for  stop-logs  or  a  gate  and 
connected  by  piping  with  a  centrifugal  pump,  so  that  by  putting 
in  the  stop-logs  or  closing  the  gate,  opening  the  proper  pipe  con- 
nections and  starting  the  pump,  any  tailrace  may  be  emptied 
and  the  turbine  unit  made  accessible  for  inspection  or  repairs. 
(See  Figs.  15,  19,  and  21.)  One  gate  will  serve  for  all  tailraces. 
The  slides  are  usually  located  at  the  mouth  or  outlet  of  the  tail- 
race,  but  it  is  better,  especially  in  cold  climates,  where  the  forma- 
tion of  ice  hi  the  slides  would  make  it  difficult  to  insert  the  stop- 
logs  or  gate,  to  have  the  slides  inside  of  the  power-house  founda- 
tion and  to  let  the  stop-logs  or  gate  down  into  the  tailrace  through 
slots  hi  the  power-house  floor,  which  slots  are  ordinarily  closed 
by  cast-iron  plates  set  into  the  floor  and  only  opened  when  required 
to  admit  the  stop-logs  or  gate.  With  this  arrangement  no  extra 
hoisting  apparatus  is  necessary,  as  the  traveling-crane  can  handle 
stop-logs  or  gate. 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.     85 

Another  rule  to  be  observed  in  connection  with  vertical  tur- 
bine units  is  that  the  weight  of  the  revolving  parts,  or  at  least 
a  portion  of  that  weight,  should  always  be  carried  by  the  water 
or  by  water  thrust  to  relieve  the  collar-bearing.  Where  it  is 
desired  to  have  the  same  portion  of  the  weight  carried  by  the 
water  at  all  stages  of  the  headwater,  the  thrust-chamber  or  pis- 


FIG.  19. — Cross-section  of  Power-house  of  the  Elektrizitaetswerk  Beznau, 
Beznau,  Switzerland.  Turbines  built  by  Th.  Bell  &  Co.,  Kriens,  Swit- 
zerland. 

ton  should  be  of  such  size  as  to  carry  the  desired  weight  at  the 
lowest  stage  of  the  headwater  and  the  water  should  be  supplied 
to  the  thrust  chamber  or  piston  by  a  separate  pipe,  the  water 
in  this  pipe  being  always  kept  at  a  pressure  corresponding  to  the 
lowest  stage  of  the  headwater  by  means  of  a  reducing-valve. 

In  Fig.  19  is  shown  a  cross-section  of  the  power-house  of  the 
Elektrizitaetswerk  Beznau,  at  Beznau,  Switzerland,  built  in  1900 


86  MODERN  TURBINE  PRACTICE. 

and  1901.  The  plant  contains  eleven  main  turbine  units,  each 
unit  being  a  vertical  triple  turbine  developing  1000  H.P.  under 
a  head  of  from  12.8  to  18.7  ft.  and  running  at  66f  revolutions. 
The  turbines  are  of  the  inflow  reaction  type,  and  to  attain  even 
the  low  speed  at  which  they  are  running  a  very  high  reaction 
had  to  be  used,  giving  a  speed  factor  of  0.925.  The  speed  regu- 
lation is  effected  by  gates  similar  to  those  shown  in  Figs.  40  and 
41,  moving  simultaneously  in  the  three  turbines  of  each  unit. 
The  end  thrust  of  the  top  and  bottom  turbines  is  partly  relieved 
by  openings  in  the  runner-disks,  while  the  water-pressure  against 
the  under  side  of  the  solid  disk  of  the  middle  turbine  carries  a, 
portion  of  the  weight  of  the  revolving  parts.  As  shown  in  the 
illustration,  the  turbine-cases  and  draft-tubes  are  formed  by  the 
concrete  foundations  of  the  power-house. 

In  Fig.  20  is  shown  a  cross-section  of  the  power-house  of  the- 
city  of  Lyons,  near  Lyons,  France.  The  plant  contains  eight  main 
turbine  units  of  1250  H.P.  each,  comprising  the  first  installation,, 
and  eight  main  units  of  a  later  design  of  1500  H.P.  each,  all  work- 
ing under  a  head  of  from  26.3  to  37.6  ft.  and  running  at  120  revo- 
lutions. The  turbines  seen  in  the  illustration  is  a  1250-H.P. 
unit  and  is  a  single  three-story  inflow  reaction  turbine  having 
a  runner  of  conical  shape,  with  the  smaller  diameter  at  the  top. 
The  bottom  and  middle  story  of  the  runner  are  used  at  all  stages 
of  the  water,  while  the  top  one  is  used  in  addition  during  flood- 
water,  when  the  head  is-  the  lowest.  The  speed  regulation  is 
effected  by  a  separate  cylinder  gate  for  each  story,  located  at 
the  entrance  or  outside  of  the  guide-bucket  rings  and  moving 
simultaneously,  but  the  gate  for  the  top  story  is  disconnected 
from  the  governor  when  that  story  is  not  in  use.  The  unit  is 
inclosed  in  a  cast-iron  case  in  the  upper  head  of  which  a  thrust- 
piston  is  located,  carrying  22  tons  of  the  weight  of  the  revolving 
parts. 

In  Fig.  21  is  shown  a  cross-section  of  the  power-house  of  the 
city  of  Geneva,  at  Chevres,  Switzerland.  This  plant  contains 
five  main  turbine  units  of  1000  H.P.  each  and  running  at  80  revo- 
lutions, comprising  the  first  installation,  and  ten  main  units  of 
a  later  design,  each  of  1200  H.P.  and  running  at  120  revolutions, 
all  turbines  working  under  a  head  of  from  14.1  to  26.2  ft.  The 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.     87 


turbine  seen  in  the  illustration  is  a  1200-H.P.  unit  and  is  a  ver- 
tical quadruple  turbine  of  the  outflow  reaction  type.  The  runners 
are  arranged  in  pairs,  the  lower  pair  alone  being  used  when  the 


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head  is  at  or  near  its  maximum.  Each  runner  has  a  separate 
cylinder  gate,  located  at  the  discharge  or  outside  of  the  runners 
and  moving  simultaneously,  but  the  gates  for  the  upper  pair 
are  disconnected  from  the  governor  when  that  pair  is  not  in  use. 
Each  pair  has  only  one  disk  hi  common  for  the  two  runners,  and 


MODERN  TURBINE  PRACTICE. 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.     89 

the  disk  being  solid,  the  water-pressure  against  its  under  side 
carries  nearly  the  whole  weight  of  the  revolving  parts.  The 
water-pressure  is  prevented  from  acting  against  the  upper  side 
of  the  runner-disks  by  making  the  disk  of  the  upper  guide-bucket 
ring  of  each  pair  of  turbines  solid  and  carrying  the  shaft  through 
by  means  of  a  stuffing-box. 

As  shown  in  the  illustration,  the  turbine-cases  and  draft-tubes 
are  formed  by  the  concrete  foundations  of  the  power-house. 

The  unusual  head-gates  seen  in  Figs.  20  and  21  will  be  con- 
sidered under  "  Head-gates." 

The  turbines  recently  installed  hi  the  electric  works  on  the 
river  Glommen  in  Norway  and  here  shown  in  Figs.  22  and  23 
are  interesting  examples  of  single  inflow  reaction  turbines  with 
vertical  shafts.1  Vertical  turbines  were  adopted  for  this  plant 
which  will  have  an  ultimate  capacity  of  50,000  H.P.,  on  account 
of  the  great  variation  in  the  tailwater,  the  floodwater  rising  to 
40.5  ft.  above  the  minimum  tailwater  level.  To  avoid  the  use 
of  multiple  turbines  to  obtain  the  required  horse-power  under 
the  available  head  and  at  the  desired  number  of  revolutions,  tur- 
bines of  a  modified  American  or  vortex  type  were  selected.  The 
turbines  work  under  a  head  of  from  39.6  to  63.1  ft.,  develop 
3000  H.P.  each  with  a  head  of  52.5  ft.  and  run  at  150  revolu- 
tions. The  speed  regulation  is  effected  by  wicket  gates.  The 
weight  of  the  revolving  parts  is  32  tons  and  is  carried  by  a 
collar-bearing,  which  is  relieved  by  oil  under  pressure;  the  pump 
furnishing  this  oil  also  operates  the  relays  of  the  speed-governors. 
The  turbine-case  is  spiral  hi  form,  made  of  steel  plate,  and  sur- 
rounds the  guide-ring  only.  The  draft-tube  is  formed  in  the  con- 
crete of  the  power-house  foundation,  and  an  egg-shaped  sewer 
is  located  above  the  draft-tube  outlets,  to  collect  any  water  which 
may  leak  into  the  basement  or  turbine  story  during  high  water, 
and  a  centrifugal  pump  is  provided  to  empty  the  sewer  when 
required. 

The  best  arrangement  for  a  single  or  multiple  horizontal  tur- 
bine with  draft-tube  or  tubes  is  an  open  turbine-chamber,  built 
of  masonry  or  concrete  or  concrete  and  steel  and  forming  a  direct 

1  Zeitsch.  d.  V.  deutsch.  Ing.,  June  20,  1903,  p.  891. 


90 


MODERN  TURBINE   PRACTICE. 


FIGS.  22  and  23. — 3000-H.P,  Turbine  for  the  Electric  Works  on  the  River 
Glommen,  Norway.     Built  by  J.  M.  Voith,  Heidenheim,  Germany. 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.     91 

continuation  or  branch  of  the  headrace  or  forebay.  This  plan 
has  been  adopted  in  recent  years  for  many  important  power-plants, 
of  which  may  be  mentioned  here  the  plants  of  the  Hudson  River 
Power  Transmission  Co.,  Mechanicsville,  N.  Y.;  the  St.  Lawrence 
Power  Co.,  Massena,  N.  Y.;  the  Michigan  Lake  Superior  Power 
Co.,  Sault  Ste.  Marie,  Mich.;  the  St.  Anthony  Falls  Water  Power 
Co.,  Minneapolis,  Minn.;  the  Montreal  Light,  Heat,  and  Power  Co., 
Montreal,  Que.,  etc. 

A  cross-section  of  the  power-house  of  the  last-named  com- 
pany, located  at  Chambly,  Que.,  is  shown  in  Fig.  24.  As  planned 
this  plant  was  to  contain  eight  main  turbine  units  of  2648  H.P. 
each,  running  at  153  revolutions  per  minute  and  working  under 
a  head  of  28  ft.,  obtained  by  damming  the  Richelieu  River. 

Each  turbine  unit  was  direct  connected  to  an  alternating 
dynamo  and  consisted  of  four  48-in.  turbines. 

Open  turbine-chambers  have  three  advantages  over  turbine- 
cases,  viz.,  the  friction  of  the  water  flowing  to  the  turbine  is  reduced 
to  a  minimum,  the  turbines  are  very  convenient  of  access,  and 
the  chambers  present  the  best  possible  conditions  for  the  speed 
regulation  of  the  turbines,  a  very  important  consideration  where 
the  water-power  is  used  to  drive  dynamos. 

The  least  permissible  depth  of  the  water  above  the  highest 
point  of  the  entrance  rim  of  the  guide-bucket  ring,  according 
to  European  practice,  is  1  meter  (3.28  ft.),  but  even  then  funnels 
may  form  and  ah-  be  sucked  through  the  turbine,  which  not  only 
causes  a  loss  in  power  and  considerable  loss  in  efficiency,  but 
also  produces  irregularities  in  the  speed  of  the  turbine.1  For 
general  practice  a  minimum  depth  of  water  of  3.5  to  4.5  ft.  should 
be  allowed  above  the  highest  point  of  the  entrance  rim  of  the 
guide-ring,  or  3.5  ft.  for  turbine-chambers  in  which  the  water 
flows  towards  the  guide-rings  at  a  high  speed,  say  5  to  6  ft.,  increas- 
ing to  4.5  ft.  for  chambers  in  which  the  velocity  of  approach  is 
low,  say  1  to  2  ft.,  as  may  often  be  the  case,  when  the  turbines 
are  running  with  part  gate. 

The  minimum  depth  of  water  above  guide-buckets  as  here 
given  applies  only  to  turbines  with  a  low  draft-head.  The  influ- 

1  Mueller.     Francis-Turbinen,  p.  161. 


92 


MODERN  TURBINE  PRACTICE. 


F 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.     93 

ence  of  the  draft-head  on  the  water  above  the  turbine  will  be 
considered  under  "The  Draft  Tube." 

Where  this  minimum  depth  cannot  be  obtained  at  all  stages 
of  the  water,  the  formation  of  air-funnels  can  be  prevented  by 
mechanically  agitating  the  water  above  the  entrance  to  the  guide- 
buckets.  Such  agitators  must  be  under  water  to  avoid  the- 
formation  of  air-bubbles.  As  a  better  plan  the  writer  would 
suggest  to  fasten,  above  the  entrance  to  the  guide-buckets,  a, 
metallic  plate  having  a  length  and  width  somewhat  larger  than 
the  outside  diameter  of  the  guide-ring.  This  plate  should  be 
horizontal,  with  its  edge  slightly  turned  up  on  the  side  from  which 
the  water  approaches,  and  its  location  should  be  centrally  above 
the  guide-ring  and  at  such  a  height  that  the  lower  surface 
is  still  in  the  water  when  the  latter  is  at  its  lowest  stage.  Such 
a  plate  would  act  the  same  as  the  shell  of  a  turbine-case,  that  is, 
it  would  seal  the  water  against  the  air.  A  board  of  the  same 
dimensions,  floating  on  the  water  and  properly  guided,  would 
serve  the  same  purpose,  but  suitable  stops  would  have  to  be  pro- 
vided to  prevent  the  board  from  going  below  the  low- water  level, 
as  occasionally  the  downward  suction  might  prove  greater  than 
the  buoyancy  of  the  board. 

Open  timber  flumes  or  timber  supports  for  turbine  settings 
should  never  be  used  excejpt  for  temporary  installations. 

In  Fig.  25  is  shown  a  longitudinal  section  of  a  horizontal  double 
turbine,  built  for  the  Isarwerk,  near  Munich,  Germany.  These 
units  are  arranged  to  be  set  in  open  turbine-chambers  and  under 
a  head  of  38  ft.  are  developing  2500  H.P.  each  and  running  at 
150  revolutions.  The  turbines  are  of  the  inflow  reaction  type, 
and  to  obtain  the  required  speed  a  high  reaction  had  to  be  used, 
giving  a  speed  factor  of  0.82.  The  speed  regulation  is  effected 
by  register  gates  of  the  design  shown  in  Figs.  3  and  4.  The  center 
bearing  of  the  main  shaft  is  dispensed  with,  the  end  bearing, 
located  inside  the  chamber  and  therefore  under  water,  is  inclosed 
and  provided  with  forced  oil  circulation,  and  the  draft-tee  and 
draft-tube  are  of  steel  plate. 

Where  such  open  flumes  cannot  be  used,  the  dome  or  casing 
inclosing  the  gate  arrangement  should  be  strengthened  to  stand 
the  water-pressure  due  to  the  head,  and  a  concentric,  or,  better,  a 


94 


MODERN  TURBINE  PRACTICE 


FIG    25. — 2500-H.P.    Turbine  for    the    Isarwerk,  near  Munich,   Germany. 
Built  by  Escher,  Wyss  &  Co.,  Zurich,  Switzerland. 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.     95 

spiral  cast-iron  case  added  to  the  turbine  surrounding  the  guide- 
ring  and  the  guide-ring  only,  in  the  same  manner  as  the  case  of  a 
centrifugal  pump  surrounds  the  fan- wheel.  The  Figs.  26  to.  34, 
illustrating  turbines  for  medium  heads,  show  various  forms  of 
such  cases.  The  entrance  to  the  turbine-case  should  have  an 
area  not  greatly  in  excess  of  the  total  entrance  area  of  all  the 
guide-buckets,  which  area  is  equal  to  the  axial  dimension  of  the 
guide-bucket  entrance  multiplied  by  the  outer  circumference  of 
the  guide-ring.  The  water  while  entering  and  inside  of  the  case 
would  thus  have  a  speed  nearly  as  high  as  when  entering  the  guide- 
buckets.  The  increased  friction  loss,  due  to  the  higher  speed 
of  the  water  in  the  turbine-case,  will  be  found  to  be  less  than  the 
losses  caused  by  the  abrupt  changes  in  the  speed  and  the  direction 
of  the  water  in  the  ordinary  steel-plate  cases. 

The  penstock,  or  the  penstock  nozzle  connected  to  the  case, 
should  be  gradually  reduced  to  the  diameter  of  the  entrance  to 
the  case.  (See  Figs.  38  and  39.) 

For  very  low  heads  and  large  powers  where  the  case  would 
be  of  very  large  dimensions,  or  where  required  for  other  reasons, 
the  case  might  be  made  of  steel  plate,  shaped  as  nearly  like  a 
cast-iron  case  as  can  be  produced  conveniently,  and  having  a 
somewhat  larger  cross-sectional  area  than  necessary  for  cast  iron. 
(See  Figs.  38  and  39.) 

Double  turbines  may  be  arranged  to  discharge  towards  each 
other,  and  then  should  have  a  case  common  to  both,  of  a  form 
as  shown  in  Figs.  36  and  37,  or,  better,  a  separate  case  for  each 
turbine,  of  a  form  as  shown  in  Figs.  38  and  39.  Double  turbines 
discharging  in  opposite  directions  would  best  be  arranged  with 
the  runner-disks  set  against  each  other  and  may  then  have  not 
only  the  case  but  also  the  guide-ring  in  common  to  both  tur- 
bines, as  shown  in  Figs.  40  and  41,  thus  requiring  a  minimum 
of  floor  space. 

The  speed-regulating  gates  employed  may  be  cylinder,  register, 
or  wicket  gates,  but  register  and  wicket  gates  are  preferable 
Care  should  be  taken  to  have  the  gates  well  balanced. 

Turbines  for  Medium  Heads. — For  medium  heads  the  writer 
considers  the  radial  inward-flow  turbine  in  a  cast-iron  case  as 
the  best  type.  These  turbines  should  be  either  reaction  or  limit 


96  MODERN  TURBINE  PRACTICE. 

turbines,  according  to  the  head,  and  should  always  be  provided 
with  draft-tubes  and  set  above  the  tail  water. 

With  medium  heads  the  use  of  vertical  turbines  will  only  be 
required  under  exceptional  conditions.  Such  conditions  were 
met  with  at  Niagara  Falls,  where  the  5500-H.P.  units  in  power- 
house No.  1  of  the  Niagara  Falls  Power  Co.  are  double  outflow 
reaction  turbines  on  vertical  shafts,  working  under  a  mean  head 
of  138  ft.  and  running  at  250  revolutions.  These  turbines  have 
no  draft-tubes  and  no  turbine-cases.1  The  turbines  in  power- 
house No.  2  of  that  company,  already  referred  to  in  connection 
with  the  thrust-piston  and  shown  in  Fig.  5,  are  single  vertical 
inflow  reaction  turbines  of  5500  H.P.  each,  working  under  a  head 
•of  156  ft.  and  running  at  250  revolutions.2  Each  turbine  is 
inclosed  in  an  almost  spherical  cast-iron  case  and  has  a  draft- 
tube,  which  is  divided  into  two  branches,  straddling  the  tailrace, 
as  a  single  center  draft-tube  would  obstruct  the  tailrace.  The 
speed  regulation  of  the  turbines  is  effected  by  a  single-cylinder 
gate  and  the  runner  has  no  additional  crowns — that  is  to  say,  is 
only  one  story  high — but  as  there  will  be  eleven  such  turbines  in 
the  power-house,  a  number  of  these  can  always  be  run  at  full 
.•gate,  while  the  remaining  units  are  started  or  stopped,  as  the 
demand  for  power  may  require.  The  weight  of  the  revolving 
parts,  as  already  stated,  is  carried  by  the  thrust-piston  at  the 
lower  end  of  the  shaft. 

The  10,500  H.P.  units  of  the  Canadian  Niagara  Power  Co. 
.are  double  vertical  inflow  reaction  turbines,  working  under  a 
head  of  136  ft.  and  running  at  250  revolutions.  Runners  and 
guides  are  practically  the  same  as  shown  in  Fig.  5,  and  the  draft- 
tubes  are  similar  in  arrangement.  The  runners  discharge  towards 
•each  other.  The  cast-iron  case  is,  of  course,  different  from  that 
shown  in  Fig.  5,  and  the  thrust-piston  is  located  above  the  upper 
turbine.3 

The  turbine  units   intended  for  the   Shawinigan  Water  and 

1  Wood.     Turbines,  p.  130. 

2  Zeitsch.  d.  V.  deutsch.  Ing.,  Aug.  31,  1901,  p.  1239;  also  an  abstract  in 
Engineering  Record,  Nov.  23,  1901,  p.  500. 

3  For  an  illustrated  description  of  these  turbines  see  Engineering  Record, 
Dec.  19,  1903,  p.  765. 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.     97 

Power  Co.,  Shawinigan,  Que.,  seen  in  the  cross-section  of  the 
power-house,  Fig.  15,  were  double  vertical  outward-flow  reaction 
turbines  developing  5500  H.P.  each  under  a  head  of  125  ft.  and 
running  at  225  revolutions.  These  turbines  were  to  have  no 
draft-tubes  or  cases,  as  they  would  always  have  been  wholly  or 
partly  submerged.  Each  runner  was  to  be  divided  into  three 
stories  and  the  speed  regulation  effected  by  cylinder  gates.  The 
disk  of  the  upper  runner  or  a  thrust-piston,  the  latter  supplied 
with  pressure- water  by  a  separate  pipe,  were  proposed  to  carry 
the  weight  of  the  revolving  parts.1 

For  horizontal  turbines  the  cases  should  resemble  in  outward 
appearance  those  of  centrifugal  pumps,  and  may  be  either  con- 
centric, like  a  Harmon  pump-case  (see  Figs.  30  and  31),  or,  better, 
spiral,  like  the  case  of  an  ordinary  centrifugal  pump  (see  Figs.  26 
to  29  and  32  to  34).  The  concentric  case  has  the  advantage 
that  it  can  always  be  used  either  right  or  left  hand,  while  the 
spiral  case  is  smaller  in  size,  permits  of  a  higher  speed  of  the  water 
flowing  through  it,  and  gives  a  slightly  better  efficiency  to  the  tur- 
bine. 

The  regulating-gates  used  should  be  either  register  gates  (see 
Figs.  3,  4,  25,  and  28  to  30)  or  wicket  gates  (see  Figs.  26,  27,  32, 
34,  40,  and  41);  the  latter  have  been  found  to  give  a  somewhat 
better  efficiency  for  part  gate-opening,  but  are  more  complicated 
than  the  register  gates. 

These  turbines  are  mostly  built  as  single  turbines,  and  for 
small  sizes  the  end  thrust  is  taken  care  of  by  a  step-  or  collar-bear- 
ing, while  for  large  sizes  the  thrust-chamber  or  piston  is  employed. 

It  is  often  asserted  that  the  close  spacing  of  the  buckets  of 
European  turbines  causes  trouble  by  choking  of  the  buckets  with 
bark,  frazil,  anchor  ice,  etc.,  but  experience  in  Europe  has  shown 
that  this  is  not  the  case,  provided  the  racks  are  kept  in  proper 
repair,  and  turbines  having  only  1  in.  clear  space  between  the 
vanes  forming  the  guide-  and  runner-buckets  are  now  running  in 
Norway  without  the  least  trouble  from  bark  or  ice. 

In  Figs.  26  and  27  is  shown  a  small  single  turbine  in  spiral 
cast-iron  case  and  intended  to  develop  104  H.P.  under  a  head 

1  See  Canadian  Engineer,  May  1901. 


98 


MODERN  TURBINE  PRACTICE. 


of  49  ft.  and  to  run  at  374  revolutions, 
modification  of  Fink's  design. 


The  wicket  gates  are  a 


Another  small  single  turbine  is  shown  in  Figs.  28  and  29.  This 
turbine  has  also  a  spiral  cast-iron  case  and  is  intended  to  develop 
200  H.P.  under  a  head  of  about  140  ft.  and  to  run  at  600  revo- 
lutions per  minute.  The  speed  is  regulated  by  register  gates. 

The  turbines  for  the  Cataract  Power  Co.,  of  Hamilton,  Ont., 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.     99 


shown  in  Figs.  30  and  31,  are  also  single  turbines,  but  in  concen- 
tric cast-iron  cases.  The  turbines  develop  3000  H.P.  each  under 
a  head  of  256  ft.,  run  at  286  revolutions,  and  give  an  efficiency 


of  80%.  To  get  a  small  runner  diameter  and  thus  a  small  tur- 
bine for  the  head  employed  and  the  required  number  of  revolu- 
tions, a  low-speed  factor  was  chosen,  viz.,  0.575.  The  turbines 


100 


MODERN  TURBINE  PRACTICE. 


-H IHfrr* 


FIG.  30. — 3000-H.P.  Turbine  for  the  Cataract  Power  Co.,  Hamilton,  Ont. 
Built  by  A.  Riva,  Monneret  &  Co.,  Milan,  Italy. 


;T'T"i  /  '  lltH.^'/.-..^ J'JSu 


rjpJffltMWW^^ 

$ 


FIG.  31.— 3000-H.P.  Turbine  for  the   Cataract  Power  Co.,  Hamilton,  Ont. 
Built  by  A.  Riva,  Monneret  &  Co.,  Milan,  Italy. 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION. 


are  regulated  by  register  gates  of  Zodel's  design,  as  shown  in 
Figs.  3  and  4.  As  will  be  seen  from  Fig.  30,  the  turbines  are  pro- 
vided with  thrust-chambers.1 


The  turbines  for  the  electrochemical  works  at  Jajce,  Bosnia, 
shown  in  Figs.  32  to  34,  are  single  turbines  in  spiral  cast-iron 

1  Zeitsch.  d.  V.  deutsch.  Ing.,  Aug.  3,  1901,  p.  1095;  also  an  abstract  in 
Engineering  News,  Nov.  14,  1901,  p.  363. 


102 


MODERN  TURBINE  PRACTICE. 


cases.  The  plant  contains  eight  units  of  1000  H.P.  each  and 
two  units  of  632  H.P.,  all  working  under  a  head  of  245  ft.  and  run- 
ning at  300  revolutions.  The  1000-  and  632-H.P.  turbines  are 
identical  in  every  respect,  except  that  the  former  have  a  width 
between  runner-crowns  of  75  millimeters  (3  ins.)  and  the  latter  a 
width  of  50  millimeters  (2  ins.),  measured  at  the  entrance  rim. 
The  1000-H.P.  turbines,  driving  three-phase  alternators,  gave 
when  tested  by  means  of  electrical  resistances,  and  assuming 
the  efficiency  of  the  alternators  as  95%,  an  efficiency  of  84% 


FIG.  34.— 1000-H.P.  Turbine  for  the  Bosnische  Elektrizitaets-Aktien-Gesell- 
schaft,  Jajce,  Bosnia.     Built  by  Ganz  &  Co.,  Budapest,  Hungary. 

with  0.8  gate-opening.  To  reduce  the  runner  diameter  and  with 
it  the  whole  turbine  to  a  minimum  size,  for  the  head  and  number 
of  revolutions  employed,  without  having  to  contend  with  the 
disadvantages  of  the  action  turbine,  the  low-speed  factor  of  0.487 
was  selected;  the  turbine  is  therefore  a  limit  turbine.  The  tur- 
bines are  regulated  by  wicket  gates  of  Fink's  design  and  have 
each  four  deflector-vanes  in  the  spiral  case  to  throw  the  water 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.  103 

towards  the  guide-buckets.  These  deflectors,  being  cast  solid 
with  the  case,  also  tie  the  case  together  and  thus  help  the  latter 
to  resist  the  water-pressure.  As  will  be  seen  from  Fig.  34,  the 
turbines  are  provided  with  thrust-chambers.  The  draft-tube  is 
of  cast  iron,  made  in  two  lengths  with  a  special  piece  to  connect 
the  two  lengths  at  the  center,  so  that  the  upper  length  may  be 
removed  without  disturbing  the  lower  one,  which  is  imbedded 
in  the  concrete.1 

The  single  turbine  in  concentric  cast-iron  case,  shown  in  Fig.  35, 
differs  greatly  in  its  general  arrangement  from  the  turbines  pre- 


FIG.  35.— 650-H.P.  Turbine  for  Messrs.  J.  &  J.  Rogers,  Ausable  Forks,  N.  Y. 
Built  by  Stilwell-Bierce  &  Smith-Vaile  Co.,  Dayton,  O. 


viously  illustrated.  On  account  of  the  end  or  axial  direction  of 
the  water  inlet  to  the  case,  the  water  approaches  the  guide-buekets 
in  a  radial  instead  of  a  more  or  less  tangential  direction,  as  is 
the  rule  with  turbines  having  a  side  inlet.  The  turbine  develops 
650  H.P.  under  a  head  of  90  ft.,  runs  at  210  revolutions,  and  has 
a  speed  factor  of  0.5.  The  regulation  is  effected  by  a  cylinder 


1  Zeitsch.  d.  V.  deutsch.  Ing.,  Oct.  6,  1900,  p.  1354;  also  Schweiz.  Bauz., 
Feb.  23,  1901,  p.  77. 


OYIL  ENGINE 
U.  of  C. 


104  MODERN  TURBINE  PRACTICE. 

gate  and  the  bearing  inside  of  the  inlet  is  inclosed  and  lubricated 
by  forcing  grease  into  it.  However,  there  is  here  no  necessity 
to  have  one  bearing  under  water,  as  this  can  be  easily  avoided 
by  dividing  the  end-inlet  nozzle  into  two  branches  and  connecting 
them  to  the  turbine-case  at  radially  opposite  sides. 

Double  turbines  on  horizontal  shafts  may  either  discharge 
towards  each  other  or  in  directions  opposite  to  each  other,  and 
the  two  turbines  may  be  either  in  a  single  case  common  to  both 
or  have  each  a  separate  case. 

The  Paderno  power-house  of  the  Edison  Electric  Co.,  of  Milan, 
Italy,  contains  seven  turbine  units  like  the  one  shown  in  Figs.  36 
and  37.  These  double  turbines  discharge  towards  each  other, 
are  inclosed  in  a  concentric  steel-plate  case  common  to  both  and 
each  unit  develops  2160  H.P.'  under  a  head  of  94.5  ft.  and  runs 
at  180  revolutions.  The  turbines  are  of  the  inflow  reaction  type, 
regulated  by  register  gates  of  Zodel's  design,  and  have  shown  an 
efficiency  of  82%.  Part  of  each  draft-tube  is  formed  by  the- 
power-house  foundations. 

In  Figs.  38  and  39  is  shown  one  of  the  double  turbine  units, 
built  for  the  carbide  works  at  Notodden  in  Norway.  The  runners 
discharge  towards  each  other,  but  each  turbine  has  a  separate 
spiral  case  made  of  steel  plate.  The  plant  at  present  contains 
two  such  units,  each  developing  1200  H.P.  under  60.7  ft.  head 
and  running  at  231  revolutions.  The  speed  regulation  is  effected 
by  wicket  gates. 

The  turbine  shown  in  Figs.  40  and  41  is  a  double  turbine,  the- 
runners  of  which  discharge  in  directions  opposite  to  each  other. 
The  runners  are  placed  back  to  back  and  have  only  one  guide- 
ring,  common  to  both  runners,  and  the  guide-ring  is  surrounded 
by  a  spiral  cast-iron  case.  This  double  turbine  develops  160  H.P. 
under  39.4  ft.  head  and  runs  at  400  revolutions,  but  although 
used  in  this  instance  under  a  low  head,  the  general  arrangement 
is  that  of  a  turbine  for  medium  heads.  The  speed  regulation  is- 
effected  by  a  peculiar  design  of  gate.  As  has  been  stated 
already,  the  entrance  end  of  the  guide-vanes  not  only  swings  like 
a  wicket  gate  but  also  moves  across  the  guide-bucket  like  a 
register  gate,  so  that  the  inner  end  of  the  movable  part  of  one 
vane  meets  the  discharge  or  inner  end  of  the  stationary  part  of 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.  105 


T-- 


PIGS.  38  and  39. — 1200-H.P.  Turbine  for  the  Carbide  Works  at  Notodden,  Norway. 
Built  by  J.  M.  Voith,  Heidenheim,  Germany. 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.  107 


108  MODERN  TURBINE  PRACTICE. 

the  next  vane  when  the  gate  is  closed.1  The  two  draft-elbows 
are  united  below  the  spiral  case,  to  connect  to  a  single  draft-tube. 

Turbines  for  High  Heads. — For  high  heads  the  writer  con- 
siders the  impulse  turbine  and  the  radial  outward-flow  full-  or 
partial-action  turbine,  or  a  combination  of  both,  all  on  horizontal 
shafts,  as  the  best  types.  Action  and  impulse  turbines  are  nearly 
always  inclosed  in  a  cast-iron  or  steel-plate  case.  If  a  draft- 
tube  is  to  be  used,  the  case  should  be  of  cast  iron,  air-tight,  and 
strong  enough  to  withstand  the  air-pressure  from  the  outside, 
and  stuffing-boxes  have  to  be  provided  for  the  shaft  where  it 
projects  through  the  sides  of  the  case.  The  draft-tube  has  here 
the  same  effect  as  if  the  amount  of  the  draft-head  had  been  added 
to  the  pressure-head;  that  is,  by  increasing  the  velocity  of  the 
water  issuing  from  the  guide-buckets  or  nozzles.  However,  as  an 
action  or  impulse  turbine  cannot  work  properly  when  submerged, 
the  water  in  the  turbine-case  or  draft-tube  has  to  be  kept  below 
and  clear  of  the  runner  and  for  impulse  turbines  also  clear  of 
the  nozzle.  With  impulse  turbines,  the  vertical  distance  from 
the  center  of  the  nozzle  discharge-opening  or  the  mean  vertical 
distance,  where  two  or  more  nozzles  are  used,  to  the  surface  of 
the  water  in  the  case  or  draft-tube  is  the  only  part  of  the  head 
that  is  really  lost,  but  this  distance  should  rarely  exceed  12  ins. 
In  the  same  manner,  the  head  lost  in  an  action  turbine  is  the 
vertical  distance  or  mean  distance  from  the  center  of  the  guide- 
bucket  discharge  opening  or  openings  to  the  surface  of  the  water 
in  the  case  of  draft-tube.  To  maintain  the  water  level  at  the 
desired  elevation  an  automatic  air-admission  valve  is  used,  as 
already  stated. 

Partial-feed  action  turbines  with  more  than  one  guide-bucket 
have  these  guide-buckets  usually  arranged  in  two  sets,  spaced  180° 
apart,  or  in  three  or  more  sets,  spaced  uniformly  around  the  circle, 
so  that  the  effects  of  the  water- jets,  such  as  the  transverse  strains 
on  the  turbine-shaft,  balance  each  other. 

The  runner  of  an  action  or  impulse  turbine  is  often  mounted 
on  the  end  of  the  turbine-shaft  and  thus  is  overhanging,  and  when 


1  Schweiz.  Bauz.,  April  27,  1901,  p.  178,  Fig.  61. 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.  109 

driving  a  dynamo  the  runner  is  frequently  keyed  to  the  end  of 
an  extension  of  the  dynamo  shaft. 

Figs.  42  to  44  show  an  action  turbine  built  for  Elektrizitaets- 
werk  at  Schwyz,  Switzerland.  The  plant  contains  four  such 
turbines,  each  developing  600  H.P.  under  a  head  of  246  ft.  and 
running  at  400  revolutions.  The  runner  is  overhanging  and 
inclosed  in  a  cast-iron  case.  The  case  has  on  the  inside  a  ridge 
or  cutting  edge,  so  as  to  divide  the  water  discharged  from  the 
runner  and  divert  it  sideways,  to  prevent  it  from  being  thrown, 
back  on  to  the  runner  (Fig.  42).  Each  turbine  is  provided  with, 
a  draft-tube  and  air-admission  valve,  the  ah*  entering  through 
the  channel  marked  ventilation  in  Fig.  42.  The  regulation  is 
effected  by  a  cylinder  gate,  stiffened  by  a  hollow  cast-iron  ring. 

The  turbine  shown  in  Figs.  45  and  46,  built  for  the  Ouiatr- 
chouan  Pulp  Co.,  Ouiatchouan,  Que.,  is  a  partial-action  tur- 
bine having  two  sets  of  guide-buckets  spaced  180°  apart.  The 
turbine  develops  1000  H.P.  under  a  head  of  240  ft.  and  runs  at 
225  revolutions.  The  runner  is  overhanging  and  inclosed  in  a 
cast-iron  case.  The  turbine  is  provided  with  a  draft-tube  and 
air-admission  valve.  The  principle  of  the  air-admission  valve  is 
very  simple  and  is  clearly  shown  in  Figs.  45  and  46.  A  vertical 
pipe  of  about  12  ins.  diameter  is  placed  alongside  the  turbine, 
with  its  top  end  connected  to  the  turbine-case  and  its  bottom 
end  to  the  draft-tube,  in  the  same  manner  as  a  water-gage  on  a 
boiler.  In  this  pipe  is  a  copper  float,  and  when  the  water  level 
in  the  turbine-case  rises  this  float  rises  also  and  opens  an  air-admis- 
sion valve  on  top  of  the  turbine-case,  and  the  water  level  and  float 
at  once  drop  and  the  valve  closes  again.  When  the  turbine  is 
running  under  a  steady  load,  the  valve  usually  comes  to  rest  in 
a  position  where  it  supplies  air  at  the  same  rate  as  it  is  absorbed 
and  carried  off  by  the  water.  A  gage-glass  or  water-gage  should 
be  attached  to  the  turbine-case  or  float-chamber  so  it  can  always 
be  seen  whether  the  air-valve  is  maintaining  the  water  at  the 
desired  level. 

The  regulation  of  this  turbine  is  effected  by  two  slides  formed 
by  the  ends  of  a  cast-iron  beam  or  girder  which  swings  on  a  pivot 
placed  in  line  with  the  turbine-shaft.  By  moving  this  girder, 
the  entrance  openings  of  one  or  more  guide-buckets  of  each  of 


110 


MODERN  TURBINE  PRACTICE. 


FIGS.  42  to  44. — 600-H.P.  Turbine  of  the  Elektrizitaetswerk,  Schwyz,  Swit- 
zerland.    Built  by  Th.  Bell  &  Co.,  Kriens,  Switzerland. 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.  Ill 


112 


MODERN  TURBINE  PRACTICE. 


the  two  opposite  sets  of  guide-buckets  are  closed  or  opened  simul- 
taneously by  these  slides. 

Figs.  47  and  48  show  a  partial-action  turbine  built  for  the 


Walliser  Industrie-Gesellschaft,  Vernayaz,  Switzerland.  The  plant 
contains  six  such  turbines,  each  developing  1000  H.P.  under  a 
head  of  1640  ft.  and  running  at  500  revolutions. 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.   113 

The  peripheral  speed  of  the  runner  is  normally  184  ft.  per 
second,  but  should  the  governor  fail  to  act,  with  no  load  on  the 
turbine,  this  speed  may  run  up  to  nearly  twice  as  much.  To 
prevent  the  runner  from  bursting,  two  heavy  steel  rings  are  shrunk 
on  to  it,  which  at  the  same  tune  aid  the  regulation  by  acting  as 
fly-wheels. 

The  lower  half  of  the  turbine-case  is  of  cast  iron  and  the  upper 
half  of  steel  plate.  The  turbine  has  but  one  guide-bucket  and 
the  regulation  is  effected  by  a  slide,  hinged  as  to  be  nearly  balanced 
in  all  positions. 

In  Figs.  49  and  50  is  shown  a  runner  of  a  spoon-turbine,  a 
type  which  may  be  said  to  stand  between  the  action  and  the 


FIGS.  49  and  50. — Runner  of  a  Spoon-turbine.      Built  by  Piccard,  Pictet 
&  Co.,  Geneva,  Switzerland. 

impulse  turbine,  as,  like  in  an  action  turbine,  the  water  flows 
radially  outward  through  the  runner,  while  the  runner-buckets 
have  the  general  shape  of  the  impulse-turbine  bucket  and,  like 
the  latter,  are  provided  with  a  ridge  or  cutting  edge  to  divide 
the  water- jet  into  halves. 

For  impulse  turbines  of  the  Pelton  type,  the  use  of  draft- 
tubes  gives  not  only  the  advantage  of  added  head  but  also  gives 
a  decreased  friction  of  the  runner  in  the  surrounding  ah-  and  a 
decreased  windage ;  that  is,  the  action  of  the  runner  as  a  centrifugal 
blower,  both  due  to  the  decreased  density  of  the  ah*  in  the  case. 

With  a  head  of  1000  ft.  and  400  revolutions  per  minute,  an 
impulse  turbine  would  have  a  diameter  of  bucket  circle  of  5  ft. 


114  MODERN  TURBINE  PRACTICE 

6  ins.  and  an  outside  diameter  of  about  6  ft.,  so  that  an  air-tight 
case  could  easily  be  provided  for  it.  With  slower  speeds  or  higher 
heads,  requiring  larger  runners,  an  air-tight  case  would  be  rather 
expensive,  and  as  the  percentage  of  gain  due  to  the  use  of  a  draft- 
tube  is  only  trifling  with  heads  of  over  1000  ft.,  draft-tubes  will 
hardly  be  used  for  impulse  turbines  larger  than  about  6  ft.  in 
diameter. 

To  regulate  the  speed  of  an  impulse  turbine  by  changing  the 
amount  of  water  supplied  to  the  turbine,  American  builders  employ 
either  a  common  gate-valve  to  throttle  the  water  before  it  reaches 
the  nozzle,  which  is  a  very  poor  arrangement  and  only  used  for 
minor  installations,  or  they  employ  the  needle-nozzle,  which  is 
a  very  simple  and  efficient  device.  The  needle-nozzle  consists 
of  a  properly  shaped  nozzle,  inside  of  which  and  concentric  with 
it  is  a  movable  needle  with  a  cone-shaped  end.  By  pushing 
this  conical  end  more  or  less  into  the  exit  opening  of  the  nozzle, 
this  opening  is  more  or  less  reduced.  For  very  high  heads  or  very 
long  penstocks,  where  a  sudden  reduction  of  the  size  of  the  nozzle 
opening  would  cause  dangerous  strains  in  the  penstock,  a  by-pass 
regulation  is  employed,  the  usual  arrangement  being  to  have 
the  nozzle  connected  to  the  penstock  or  branch  pipe  by  a  flexible 
joint,  and  to  deflect  the  nozzle  more  or  less  away  from  the  buckets, 
in  proportion  to  the  reduction  of  the  load  on  the  turbine.  The 
flexible  pipe-joint  of  deflecting  nozzles,  usually  a  ball  joint,  used 
in  connection  with  the  high- water  pressures  considered  here,  is 
frequently  a  source  of  much  trouble.  As  deflecting  nozzles  at 
all  times  discharge  the  water  required  for  the  maximum  load, 
they  are  very  wasteful  when  used  for  variable  loads,  and  to  avoid 
this  needles  have  been  employed  in  some  instances  in  connection 
with  deflecting  nozzles.  In  such  cases  the  needle,  usually  operated 
by  hand,  takes  care  of  the  larger  fluctuations  and  the  deflection 
of  the  nozzle,  controlled  by  the  governor,  of  the  smaller  fluctua- 
tions. 

The  cross-section  of  all  the  nozzles  used  by  American  builders 
is  round,  while  the  majority  of  European  builders  use  rectangular 
nozzles. 

A  rectangular  needle-nozzle  might  be  employed  having  a 
needle  to  conform  to  the  section  of  the  nozzle,  but  European 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.  115 

builders  always  use  a  tongue  in  connection  with  rectangular 
nozzles. 

A  tongue-nozzle  has  two  of  its  sides  parallel,  while  one  of  the 
two  remaining  sides  is  hinged  and  forms  the  tongue,  which  works 
like  the  beak  of  a  bird,  as  shown  in  Figs.  51,  52,  and  55.  As  will 
be  seen  from  the  illustrations,  both  nozzles  are  provided  with  a 
temporary  by-pass  —  that  is  to  say,  a  by-pass  which  opens  hi  the 
same  proportion  as  the  nozzle  opening  is  decreased  —  but  the 
governor  slowly  closes  the  by-pass  again  as  soon  as  the  nozzle 
opening  stops  to  decrease. 

The  water-pressure,  tending  to  force  the  tongue  outward  ^  is 
not  as  great  as  might  be  supposed,  as  at  the  point  where  the 
tongue  is  located  most  of  the  head  of  the  water  has  already  been 
converted  into  velocity.  The  tongue  can  also  be  hinged  in  such 
a  manner  as  to  be  partly  balanced.  For  the  same  cross-sectional 
area,  the  perimeter  of  a  rectangular  nozzle  is  greater  than  the 
perimeter  of  a  round  one,  but  the  presence  of  the  needle  hi  the 
round  nozzle  will  have  the  effect  that  the  friction  loss  in  a  needle- 
nozzle  will  be  fully  as  great  as  in  a  tongue-nozzle. 

Rectangular  nozzles  of  European  builders  resemble  in  shape 
the  turbine  guide-buckets  and  have  been  made  as  large  as  3x6  ins. 
at  the  discharge-opening.  In  fact  the  action  and  impulse  tur- 
bines are  approaching  each  other  more  and  more  in  European 
practice,  and  will  soon  be  fused  into  one  single  type,  retaining 
the  best  features  of  both. 

To  obtain  good  efficiency,  nozzles  and  runner-buckets  must 
be  carefully  designed  and  dimensions  and  shape  adapted  to  each 
other.1 

When  draft-tubes  are  used  with  by-pass  regulation,  the  dis- 
charge from  the  by-pass  must  not  strike  the  water  surface  in  the 
turbine-case  or  draft-tube,  as  otherwise  it  would  throw  the  water 
into  such  commotion  as  to  interfere  with  the  proper  working  of 
the  runner.  To  prevent  this,  the  by-pass  should  be  located  out- 
side the  turbine-case,  as  shown  in  Fig.  55,  or  baffle-plates  used; 


paper  by  Mr.  G.  J.  Henry,  Jr.,  "Tangential  Water-wheel  Efficien- 
cies," read  before  the  Pacific  Coast  El.  Transm.  Assoc.,  June  16,  1903;  also 
an  abstract  in  Engineering  News,  Oct.  8,  1903,  p.  322. 


116 


MODERN  TURBINE  PRACTICE. 


or  spouts  so  arranged  as  to  cany  the  by-pass  discharge  below 
the  surface  of  the  water  in  the  case  or  draft-tube.  , 


FIG.  53. 

FIGS.  51  to  53.— 360-H.P.  Impulse  Turbine.      Built  by  Th.   Bell  &  Co., 
Kriens,  Switzerland. 

In    Figs.  51  to   53  is  shown  an  impulse  turbine   developing 
360  H.P.  under  a  head  of  492  ft.  and  running  at  500  revolutions. 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.  117     1 


FIG.  54. 


FIG.  55. 


118 


MODERN  TURBINE  PRACTICE. 


The  turbine  is  provided  with  a  temporary  by-pass,  which  is  opened 
and  closed  by  a  slide.  The  operation  of  the  governor  will  be 
considered  under  "  Governors  and  Speed  Regulation." 

In  Figs.  54  to  56  is  shown  one  of  the  units  of  the  Elektrizitaets- 
werk  Kubel,  near  St.  Gallen,  Switzerland.  Each  unit  consists 
of  a  double  impulse  turbine,  developing  500  H.P.  under  a  head 


FIG.  56. 

FIGS.  54  to  56.—  500-H.P.  Impulse  Turbine  for  the  Elektrizitaetswerk  Kubel, 
near  St.  Gallen,  Switzerland.  Built  by  Escher,  Wyss  &  Co.,  Zurich, 
Switzerland. 

of  295  ft.  and  running  at  375  revolutions.  Each  unit  is  inclosed 
in  a  cast-iron  case  and  has  a  draft-tube.  The  temporary  by-pass 
discharges  outside  of  the  case  and  the  water  enters  the  latter  side- 
ways and  below  the  water  level.  The  float  for  operating  the  air- 
admission  valve  is  located  in  a  chamber  not  directly  attached 
to  the  case.  The  variation  of  the  water  level  in  the  case  is  less 
than  2  ins. 


MODERN  TURBINE  TYPES  AND  THEIR  CONSTRUCTION.  119 

One  of  the  most  interesting  installations  of  impulse  turbines 
is  the  electric  plant  at  Vouvry,  near  Geneva,  Switzerland.  There 
are  at  present  four  turbines  in  operation,  each  developing  500  H.P., 
running  at  1000  revolutions  and  utilizing  a  head  of  3117  ft.,  equal 
to  a  pressure  of  1350  Ibs.  per  sq.  in.,  the  highest  head  of  any  exist- 
ing development.  Two  of  the  turbines  are  built  by  the  Socie*te 
de  Constructions  Me"caniques  of  Vevey,  Switzerland,  and  resemble 
inward-flow  action  turbines.  The  two  remaining  turbines,  built 
by  M.  Duvillard,  Lausanne,  Switzerland,  resemble  impulse  tur- 
bines of  the  Pelton  type,  but  the  ridge  or  cutting  edge,  to  divide 
the  water-jet  into  halves,  is  placed  inside  of  the  nozzle  instead 
of  in  the  runner-buckets,  and  the  jet  therefore  leaves  the  nozzle 
already  divided.  The  outer  edge  of  the  very  thick  cast-iron  disk, 
on  each  side  of  which  the  runner-buckets  are  located,  takes  the 
place  of  the  bucket-ridge.  The  water  flows  inward,  leaving  the 
buckets  at  their  inner  edge.  The  outside  diameter  of  the  runner 
is  47 J  ins.1 

Manufacture  of  Turbines. — The  manufacture  of  such  modern 
high-class  turbines  as  have  here  been  illustrated  and  described 
would  best  be  taken  up  by  a  builder  of  large,  high-grade  steam- 
engines  or  similar  machines,  as  the  work  would  be  of  the  same 
character.  The  large  planers,  horizontal  and  vertical  boring- 
mills,  etc..  of  the  engine-shop  might  be  used  by  the  turbine  depart- 
ment until  increased  sales  warrant  the  purchase  of  such  tools 
for  the  sole  use  of  the  turbine-shop.  The  manufacture  of  tur- 
bine-pumps would  naturally  form  a  branch  of  the  turbine-manu- 
facture. Although  the  guides  and  runners,  as  now  made  by 
many  manufacturers  of  American  turbines,  give  such  high  effi- 
ciencies under  low  heads  that  no  appreciable  improvement  is 
to  be  expected  in  the  future,  and  the  guide  and  runner  patterns, 
involving  a  great  outlay,  might  be  used  for  modern  low-head 
turbines,  yet  the  writer  thinks  an  engine-builder  more  likely  to 
produce  a  high-class  turbine  than  the  average  turbine  manu- 
facturer, as  the  latter  might  find  it  difficult  to  refrain  from  using, 
besides  guides  and  runners,  most  of  the  rest  of  his  old  patterns 
and  from  generally  returning  to  his  old  shop  practice. 

1  See  Engineering  News,  Nov.  27,  1902,  p.  439;  also  Engineering  Record, 
Nov.  29,  1902,  p.  516. 


120  MODERN  TURBINE  PRACTICE. 

Manufacturers  of  turbines  would  best  contract  for  the  whole 
hydraulic  equipment  of  power-plants,  building  the  turbines  and 
governors  and  subletting  penstocks,  head-*gates,  structural-steel 
work,  etc.  If  this  is  not  done,  the  manufacturer  should  furnish 
the  design  for  the  hydraulic  equipment  outside  of  the  turbines 
and  governors,  or  be  at  least  consulted  in  regard  to  it,  as  even 
with  turbines  of  the  highest  efficiency  the  total  efficiency  of  a 
plant  may  be  low,  owing  to  faulty  design  of  the  rest  of  the  plant. 
But  outside  from  the  efficiency,  the  general  arrangement  of  the 
plant  will  also  influence  the  accessibility,  freedom  from  interrup- 
tions, breakdowns,  trouble  with  floating  rubbish,  ice,  etc.  The 
present  practice  of  some  turbine  builders  to  promote  water- 
power  companies  for  the  sake  of  selling  turbines  and  equipping 
such  plants  with  from  two  to  four  times  the  number  of  turbines 
that  can  possibly  be  run  at  times  of  low  water  is  strongly  to  be 
condemned. 

The  designing  of  turbines  is  rather  more  difficult  than  the 
designing  of  steam-engines,  for  example.  The  location  of  a  steam- 
plant  can  usually  be  chosen  and  the  designer  can  also  choose  the 
pressure  and  the  amount  of  steam  and  the  number  of  stages  of 
expansions,  but  the  turbine  designer  has  to  contend  with  a  loca- 
tion, height  of  head  and  amount  of  water  fixed  by  nature  and  is 
required  to  utilize  the  head  in  a  single  stage.  It  is  therefore 
important  to  the  turbine  manufacturer  to  have  an  experienced 
designing  and  calculating  engineer,  occupying  a  position  similar 
to  that  of  the  engineer  who  makes  the  calculations  and  strain- 
sheets  in  bridge  works. 

In  going  into  the  manufacture  of  modern  turbines,  it  would 
be  bad  policy  to  design  and  make  patterns  for  turbine  sizes  as 
orders  received  may  call  for.  The  proper  way  to  bring  out  a 
new  line  of  machinery  involves  a  large  amount  of  preliminary 
office  work.  To  begin  with,  after  collecting  all  available  books, 
papers,  data,  etc.,  on  the  subject  and  consulting  manufacturers 
whose  machinery  is  likely  to  be  direct  connected  to  turbines, 
especially  the  builders  of  dynamos,  as  to  speeds,  horse-power,  etc., 
a  number  of  different  styles  of  each,  the  low-,  medium-,  and  high- 
head  turbine,  should  be  designed.  Having,  after  a  very  careful 
consideration  of  all  the  points  involved,  selected  the  style  to  be 


MODERN  TURBINE  TYPES  AND    THEIR  CONSTRUCTION.  121 

adopted  for  each  range  of  head,  a  small-,  medium-,  and  large-size 
turbine  for  each  range  of  head  should  be  designed,  the  dimen- 
sions of  one  or  two  intermediate  sizes  calculated,  and  curves  plotted 
from  the  results.  These  curves  give  at  once  all  the  principal 
dimensions  and  correct  proportions  for  any  size  of  turbine  between 
the  smallest  and  the  largest,  and  a  uniform  line  of  stock  sizes 
may  then  be  chosen  for  each  range  of  head,  say  by  having  the 
runner  diameter  in  multiples  of  3  ins.  up  to  48  ins.  and  in  mul- 
tiples of  6  ins.  up  to  72  ins.,  all  sizes  to  be  made  both  right  and 
left  hand  and  sizes  over  72  ins.  to  be  special  and  built  to 
order.  With  such  a  line  of  sizes,  all  conditions  of  head,  power,  and 
revolutions  could  be  met  and  high  efficiencies  obtained  in  all  cases. 

The  turbine-cases  should  be  designed  at  the  start  to  take  guides 
and  runners  of  different  widths  of  crown  or  axial  dimension  and 
to  permit  the  use  of  the  same  patterns  of  spiral  cases  for  both 
right-  and  left-hand  turbines.  The  supporting  brackets  of  the 
cases  should  be  loose  on  the  patterns,  so  that  the  inlet-nozzle 
may  be  placed  in  any  desired  direction  to  suit  local  conditions. 
Excepting  the  smaller  sizes  of  turbines,  the  guide-  and  runner- 
vanes  with  their  crowns  should  be  cast  in  the  form  rings  and 
bolted  to  the  case  and  runner-disk  or  spider  respectively.  One 
pattern  for  each  diameter  of  guide-  and  runner-ring  can  usually 
be  made  to  serve  for  any  width  of  crown,  from  the  smallest  that 
is  permissible  to  the  largest  that  the  case  will  take  and  for  both 
right-  and  left-hand  turbines. 

The  power  of  the  turbine  will,  of  course,  vary  in  direct  pro- 
portion to  the  width  of  the  crown,  but  should  the  least  permissible 
width  of  crown  still  give  a  power  in  excess  of  the  required  amount 
the  quantity  of  the  water  flowing  through  the  turbine  may  be  still 
further  reduced  by  decreasing  the  number  of  guide-buckets,  that 
is,  changing  the  turbine  to  a  partial-feed  turbine.  However,  as 
reaction  turbines  do  not  give  good  efficiencies  with  partial  feed, 
action  turbines  should  be  employed  in  such  cases. 

The  width  and  curvature  of  the  guide-  and  runner-vanes  should 
be  determined  for  each  individual  turbine,  to  suit  the  quantity 
of  water  and  height  of  head  to  be  utilized.  It  may  be  repeated 
here  that  reaction  turbines  can  be  designed  to  give  their  maxi- 
mum efficiency  at  any  desired  gate-opening. 


122  MODERN  TURBINE  PRACTICE. 

The  use  of  cast  guide-  and  runner-vanes  requires  the  making 
of  a  separate  core-box  for  each  width  and  shape  of  vane.  Except 
for  limit  turbines,  where  thick  vanes  are  required,  the  use  of  steel- 
plate  vanes  for  both  guide-  and  runner-buckets  is  to  be  preferred, 
and  such  vanes  are  used  by  most  European  manufacturers.  The 
impact  of  the  water  striking  the  initial  edge  of  the  runner-vanes 
not  only  causes  a  loss,  but  also  gives  rise  to  irregularities  in  the 
flow  of  the  water,  for  which  reasons  this  edge  should  be  as  thin 
as  possible,  a  condition  favorable  to  the  use  of  steel-plate  vanes. 
Steel-plate  vanes  are  strong,  hard,  and  smooth,  but  corrode  and 
pit  more  readily  than  cast-iron  vanes.  Such  steel-plate  vanes, 
after  being  cut  to  size,  are  brought  to  the  required  curvature 
by  being  heated  and  pressed  in  cast-iron  dies  and  are  then, 
while  still  hot,  placed  in  the  runner  or  guide-ring  mold  and 
cast  in. 

Runners  and  guide-rings  are  molded  by  means  of  molding- 
machines  to  avoid  deviation  from  the  exact  spacing,  position 
and  direction  of  the  vanes,  and  to  insure  the  correct  shape  of  the 
ring. 

To  obtain  good  efficiencies  with  any  type  of  turbine  requires 
high-class  castings,  especially  the  inner  surfaces  of  the  bucket- 
and  other  water-passages  should  be  perfectly  smooth.  The  mate- 
rial for  the  guide-  and  runner-rings  should  be  a  hard  quality  of 
cast  iron  for  low  heads  and  bronze  or  steel  casting  for  medium 
and  high  heads.  The  clearance  of  the  runners  of  reaction  tur- 
bines should  not  be  larger  than  -fa  in.  for  small  and  medium  size 
and  j1^  in.  for  the  largest  size  of  runners.  Action  turbines  may 
have  larger  clearances. 

With  the  American  or  low-head  type  of  turbine  the  required 
power  at  a  given  number  of  revolutions  is  at  present  obtained 
by  using  one  or  more  turbines  on  the  same  shaft,  or  by  varying 
the  width  between  crowns  or  axial  dimension  of  the  buckets  to 
suit,  or,  if  the  necessary  reduction  of  bucket  area  is  only  slight, 
by  means  of  the  regulating-gates,  and  it  is  likely  that  these  means 
will  be  employed  in  the  future  for  this  type  of  turbines.  The 
runners  and  guides  are  usually  cast  solid,  using  patterns  and 
core-boxes,  although  some  manufacturers  use  built-up  runners, 
the  vanes  being  cast  singly  or  in  groups  of  two  to  three.  Vanes 


MODERN  TURBINE  TYPES  AND  THEIR   CONSTRUCTION.  123 

of  steel  plate,  both  for  guides  and  runners,  are  rarely  used  in 
American  practice. 

With  the  medium  head  or  European  type  of  turbine  the 
required  power  at  a  given  number  of  revolutions  is  obtained  by 
using  one  or  more  turbines  on  the  same  shaft  or  by  varying  the 
width  between  the  crowns  of  guides  and  runners. 

With  the  high-head  type — that  is,  action  and  impulse  turbines — 
the  required  power  at  a  given  number  of  revolutions  is  obtained 
by  using  one  or  more  turbines  on  the  same  shaft,  by  using  one 
or  more  guide-buckets  or  nozzles  for  each  turbine,  and  by  varying 
the  size  of  the  buckets  and  nozzles. 


CHAPTER  VI. 
ACCESSORIES  TO  TURBINES. 

The  Draft-tube. — Although  draft-tubes  have  only  come  into 
general  use  hi  comparatively  recent  years,  their  great  advantage 
is  now  universally  recognized,  as  only  the  draft-tubes  made  it 
practically  possible  to  employ  turbines  on  horizontal  shafts  or 
to  set  turbines  above  the  tailwater  without  losing  part  of  the 
head. 

In  considering  the  effect  of  the  draft-tube  it  should  be  borne 
in  mind  that: 

A  given  static  head  may  exist  either  wholly  in  the  form  of 
pressure  or  pressure-head,  or  wholly  in  the  form  of  vacuum  or 
suction  or  draft-head,  or  part  of  the  head  may  be  in  the  form  of 
pressure-head  and  the  remainder  hi  the  form  of  draft-head. 

Also,  a  given  head  may  exist  wholly  in  the  form  of  pressure 
or  static  head,  or  wholly  in  the  form  of  velocity,  or  part  of  the 
head  may  be  hi  the  form  of  pressure  and  the  remainder  in  the 
form  of  velocity,  and  pressure  can  be  converted  into  velocity 
or  velocity  into  pressure. 

The  effect  of  a  draft-tube  on  a  turbine  may  be  compared  to 
the  effect  of  a  condenser  on  a  steam-engine,  as,  like  the  condenser, 
the  draft-tube  removes  part  of  the  back  or  counter  pressure  due 
to  the  pressure  or  weight  of  the  atmosphere,  while  the  water-column 
above  the  turbine  acts  like  the  live  steam  behind  the  engine-piston. 
The  means  employed  for  partially  removing  the  back  pressure 
are  in  the  case  of  the  turbine  the  suction  caused  by  a  hanging 
water-column,  and  in  the  case  of  the  steam-engine  the  condensa- 
tion of  steam,  creating  a  partial  vacuum. 

As  the  hanging  water-column  in  the  draft-tube  is  counter- 
balanced or  held  in  equilibrium  by  the  pressure  of  the  atmosphere, 

124 


ACCESSORIES  TO  TURBINES.  125 

its  height  or  head  cannot  be  greater  than  that  of  a  water-column 
exerting  on  its  base  a  pressure  equal  to  the  atmospheric  pressure. 
At  sea  level  the  pressure  of  the  atmosphere  is  14.72  Ibs.  per 
square  inch,  or  2119  Ibs.  per  square  ft.,  and  this  will  hold  in  equilib- 
rium a  column  of  water  34  ft.  in  height  if  the  water  is  at  rest, 
but  if  the  water  is  in  motion  then  the  atmospheric  pressure  has 
also  to  counterbalance  that  height  or  head,  which  is  contained 
in  the  water  in  the  form  of  velocity,  and  the  height  of  the  column 
thus  balanced  will  be  34  ft.,  less  the  velocity-head,  corresponding 

Cf2 

to  the  speed  of  the  water,  or  34—^-,  in  which  c/  is  the  draft-tube 

speed,  that  is,  the  velocity  of  the  water  at  exit  from  the  lower  end  of 
the  draft-tube  in  feet  per  second  and  g  is  the  acceleration  of  gravity, 
equal  to  32.16.  With  the  speed  cf  equal  to  46.8  ft.,  the  velocity- 
head  becomes  34  ft.  and  the  height  of  the  water-column  that  will 

be  balanced  by  the  atmospheric  pressure  becomes  34—        ' 


which  is  equal  to  zero. 

In  a  draft-tube  the  water-column  can,  therefore,  not  have  a 

cf2 
greater  height  in  feet  than  34—^-,  and  if  the  vertical  length  of 

the  draft-tube  is  more  than  that,  the  water  surface  in  it  will  remain 

Cf2 

Sit  an  elevation  of  34—^-,  and  the  part  of  the  draft-tube  above 

this  level  will  contain  a  vacuum,  which  means  a  loss  of  head  equal 
to  the  height  of  the  empty  space. 

The  considerations  and  figures  just  given  are  theoretical  only, 
and  have  to  be  modified  in  practice. 

However,  not  the  whole  of  this  draft-head  can  be  utilized  in  the 
turbine,  and  to  obtain  the  effective  draft-head  the  sum  of  the  various 
losses  has  to  be  deducted  from  the  total  draft-head  of  34  ft.  These 
losses  are  due  to  the  friction  of  the  water  in  the  draft-tube,  to  the 
change  in  the  speed  of  the  water  between  the  turbine-runner  and  the 
lower  end  of  the  draft-tube,  and  to  the  momentum  or  velocity  still 
contained  in  the  water  while  leaving  the  draft-tube. 

It  should  be  mentioned  here  that  the  laws  governing  the  action 
of  draft-tubes  also  apply  to  the  suction  of  pumps  and  in  this  con- 
nection may  be  stated  thus  :  The  vertical  distance  in  feet  to  which 


126  MODERN  TURBINE  PRACTICE. 

s2 
water  can  be  raised  by  suction  is  theoretically  34——,  in  which  s  is 

the  velocity  of  the  water  with  which  it  enters  the  suction-pipe  in 
feet  per  second.  From  this  theoretical  height  has  to  be  deducted 
the  entrance-head  for  the  suction-pipe  and  the  losses  due  to  friction 
and  bends  in  the  suction-pipe.  The  result  has  to  be  further  reduced 
for  the  reason  that  a  pump  cannot  produce  a  perfect  vacuum.  It 
will  be  seen  that  a  larger  suction-pipe  with  flaring  end  not  only 
means  a  decreased  friction  loss,  but  also  a  decreased  loss  in  velocity- 
head  and  entrance-head. 

Air-bubbles  rise  in  water  with  a  speed  of  about  12  ins.  per  second, 
and  to  prevent  such  bubbles  from  rising  inside  of  a  draft-tube  and 
to  carry  off  the  air,  when  starting  a  turbine  with  the  draft-tube 
filled  with  air,  the  speed  per  second  of  the  water  while  leaving  the 
draft-tube  should  not  be  less  than  2  to  3  ft.  As  turbines  are  often 
required  to  run  continuously  with  part  gate-opening  it  may  be  stated 
that: 

The  minimum  draft-tube  speed  c/  —  that  is,  the  speed  with  which 
the  water  issues  from  the  lower  end  of  the  draft-tube  —  should  never 
be  less  than  2  to  3  ft.  per  second,  with  the  minimum  gate-opening  at 
which  the  turbine  may  be  required  to  run  for  any  length  of  time 
or  continuously.  In  practice  it  is  usual  to  employ  a  draftrtube 
speed  of  2  ft.  for  low  heads,  increasing  it  to  3  ft.  for  heads  of  about 
100  ft.  and  to  4  to  6  ft.  for  heads  of  about  500  ft. 

The  absolute  velocity  in  feet  per  second  with  which  the  water 
issues  from  the  runner-buckets  —  that  is,  the  velocity  relative  to  a 
stationary  object  —  may  be  taken  as 


for  large-size  turbines  and  low  heads,  say  10  ft.;  as 


for  medium-size  turbines  and  medium  heads,  say  100  ft.;  and  as 


ACCESSORIES  TO  TURBINES. 


127 


for  small-size  turbines  and  high  heads,  say  500  ft.,  in  which  H  is 
the  total  effective  head  in  feet  acting  on  the  turbines.  This  is  for 
turbines  of  the  European  type.  The  writer  could  find  no  reliable 
data  in  regard  to  the  absolute  discharge  velocity  of  American 
turbines,  but  it  may  be  stated  that  these  velocities  are  higher  for 
the  American  than  for  the  European  type. 

The  heads  corresponding  to  these  discharge  velocities  are  entirely 
lost,  except  when  draft-tubes  are  used,  which  discharge  the  water 
at  lower  speeds;  or,  stating  this  in  another  way,  of  two  similar 
turbines  working  under  the  same  head,  but  one  set  above  the  tail- 
water  and  provided  with  a  properly  designed  draft-tube,  while 
the  other  is  set  on  or  below  the  level  of  the  tailwater,  and  not 
provided  with  a  draft-tube,  the  turbine  using  the  draft-tube  will 
always  give  the  higher  efficiency,  and  the  efficiency  of  a  turbine 
working  on  or  below  the  level  of  the  tailwater  may  be  increased 
by  the  addition  of  a  draft-tube,  as  the  draft-tube  acts  in  exactly 
the  same  manner  as  the  Boyden  diffuser,  making  power  available 
out  of  the  water  discharged  from  the  runner  by  retarding  the 
velocity  of  the  water. 

A  few  examples  will  illustrate  this.  Assuming  the  heads  H  to 
be  10,  100,  and  500  ft.  and  the  corresponding  draft-tube  speeds 
Cf,  equal  to  2,  3,  and  4  ft.,  then  the  velocity-heads  will  be 

hf=Y~,  or  0.062;  0.140  and  0.248ft.  respectively.- 

If  ha  is  the  velocity-head  for  the  absolute  velocity  of  discharge 
from  the  runner-buckets  ca,  and  G  is  the  gain  in  head,  due  to  the 
retardation  of  the  water  by  the  use  of  a  draft-tube,  then  we  have: 


H=  

10  ft 

100  ft 

500  ft 

C«2 

=  7.23  ft. 
0  2852  X  H 

=  16.05  ft. 
—0  2002V  // 

=  29.  97  ft, 
—  0  1fi72  V  TT 

a     2<7      

=0.796  ft. 

=  4  ft 

=  13.94  ft. 

c       2g       h»  hf   ... 

G  in  per  cent  of  H  =  

.  /o4  It. 

7.34% 

—        O.oO  It. 

=     3  86% 

—    13.o9  it. 

=     2.74% 

The  gains  here  shown  are  theoretical  only  and  cannot  be  reached 
in  practice,  but  a  well-arranged  draft-tube  should  realize  75%  or 
more  of  the  theoretical  gain. 


128 


MODERN  TURBINE  PRACTICE. 


Conical  or  flaring  draft-tubes,  changing  the  speed  of  the  water 
gradually,  should  always  be  used,  and  the  present  practice  of  having 
the  same  cross-sectional  area  for  the  entire  length  of  the  draft- 
tube  must  be  condemned,  as  the  water,  issuing  from  the  runner 
with  a  velocity  several  times  greater  than  the  velocity  of  the  water- 
column  in  the  draft-tube,  strikes  the  latter  and  is  so  suddenly 
retarded  that  most  of  the  power  made  available  by  the  retardation 
of  the  water  is  lost  in  the  shock. 

It  must  also  be  borne  in  mind  that  to  reduce  the  speed  with 
which  the  water  leaves  the  runner  to  the  speed  with  which  it  leaves 
the  draft-tube  requires  a  certain  minimum  length  of  draft-tube, 
this  minimum  length  being  the  greater  the  larger  the  diameter 
of  the  draft-tube  is. 

No  reliable  data  seem  to  have  been  published  regarding  the 
minimum  length  of  draft-tube  required  for  a  given  reduction  in 
the  velocity  of  the  water,  and  the  writer  has  therefore  compiled 
the  following  table  for  round  draft-tubes  of  different  diameters. 
The  table  gives  the  greatest  permissible  angle  of  flare,  that  is, 
the  angle  which  the  opposite  sides  or  walls  of  the  draft-tube  form 
-with  each  other,  also  the  approximate  increase  in  diameter  and 
;area  in  a  length  of  10  ft. 

MAXIMUM  FLARE  OF  DRAFT-TUBES. 


Small  End. 

Angle  of 
Flare. 

Large  End. 

Proportion 
of  Areas. 

Diameter. 

Area. 

Diameter. 

Area. 

2  ft 

3.14 

15° 

4.5  ft. 

15.90 

1:5.05 

4  " 

12.57 

23° 

8.0  ' 

50.26 

1:4.00 

6  " 

28.27 

29° 

11.0  ' 

95.03 

1:3.36 

8  " 

50.26 

33° 

14.0  ' 

153.94 

1:3.06 

10  " 

78.54 

36° 

16.5  ' 

213.82 

1:2.72 

12  " 

113.10 

38° 

19.0  ' 

283.53 

1:2.51 

In  general,  it  may  be  said  that  a  short  draft-tube  may  have  a 
greater  angle  of  flare  than  a  long  draft-tube. 

It  will  sometimes  prove  an  advantage  to  increase  the  length 
of  the  draft-tube,  without  increasing  the  draft-head,  by  curving 
or  inclining  the  draft-tube,  as  this  not  only  gives  a  greater  length 
in  which  to  reduce  the  velocity  of  the  water,  but  also  permits 


ACCESSORIES  TO  TURBINES. 


129 


to  discharge  the  water  in  the  desired  direction,  besides  an  inclined 
draft-tube  may  often  save  some  of  the  tailrace  excavation.  On 
the  other  hand,  the  water  hi  an  inclined  draft-tube  will  crowd 
towards  the  lower  or  bottom  side  of  the  tube,  and  to  keep  the 
tube  running  full,  the  speed  of  the  water  has  to  be  higher  than 
in  a  vertical  draft-tube,  and  this  increase  in  speed  must  be  the 
greater  the  more  the  direction  of  the  centre  line  of  the  draft- 
tube  is  off  the  vertical. 

The  draft-head  that  can  be  empolyed  in  practice  is  only  a  part 
of  the  theoretical  limit  of  34  ft.  less  the  velocity-head,  the  prac- 
tical limit  decreasing  with  increasing  diameters  of  draft-tube. 

The  writer,  by  computing  the  equivalents  in  English  measure- 
ment of  the  metric  values  of  a  table  given  in  a  German  standard 
work  on  turbines  and  plotting  a  curve  from  the  results,  has  deduced, 
the  following  table  of  the  greatest  draft-head  that  may  be  employed 
in  practice,  under  average  conditions,  and  for  different  diameters 
of  draft-tube.1 


Diameter  of  draft-tube  in  ft.  .      0.5 
Draft-head  in  ft                        31 

1 
29  5 

1.5 

28  1 

2 

26  7 

2.5 
25  3 

3 
23  9 

3.5 
22  6 

Diameter  of  draft-tube  in  ft  

4 

4.5 

5 

6 

7 

8 

Draft-head  in  ft 

21  4 

20  2 

19 

17 

15  4 

14  2 

Diameter  of  draft-tube  in  ft  ....... 

9 

10 

11 

12 

13 

14 

Draft-head  in  ft  

13  2 

12  3 

11  4 

10  6 

9  8 

9 

From  the  draft-heads  here  given  the  velocity-head,  correspond- 
ing to  the  speed  with  which  the  water  leaves  the  draft-tube,  or 

c/2 
hj=-j--,  has   to  be  deducted,  and  the  result  will  be  the  greatest 

permissible  draft-head  to  be  employed.  For  conical  draft- tubes 
this  table  shows  the  greatest  height  above  the  tailwater  at  which 
a  given  diameter  of  draft-tube  may  be  used;  this  height  is,  of 
course,  to  be  corrected  for  the  velocity  with  which  the  water  is 


1  See  Meissner.     Hydraulische  Motoren,  vol.  2,  p.  212. 


130  MODERN  TURBINE  PRACTICE. 

discharged  irom  the  lower  end  of  the  draft-tube  in  the  same  way 
as  just  stated.     For  example,  a  conical  draft-tube  must  not  be 

Cf2 

more  than  9  ft.  in  diameter  at   a  height  of  13.2-^-  ft.   above 

the  tailwater  level. 

Under  average  conditions  these  figures  must  not  be  exceeded 
if  perfect  working  of  the  draft-tube  is  to  be  insured,  but  in  general 
a  higher  draft-head  may  be  used  with  turbines  with  steady  loads 
and  always  working  with  their  full  capacity,  while  with  turbines 
liable  to  great  and  violent  fluctuations  in  their  loads  and  working 
at  times  only  with  small  fractions  of  their  full  capacity  the  draft- 
head  should  be  smaller  than  given  in  the  table. 

A  draft-tube  will  work  better  in  connection  with  a  vertical 
turbine  discharging  directly  into  the  tube  than  with  a  horizontal 
turbine  connected  with  the  tube  by  a  draft  tee  or  elbow.  Some 
engineers  therefore  use  for  horizontal  turbines  only  from  66  to 
75%  of  the  permissible  draft-head  given  in  the  table,  but  this 
reduction  is  not  necessary. 

Where  it  is  essential,  a  higher  draft-head  may  be  employed 
by  using  two  smaller  draft-tubes  instead  of  one  larger  one,  or 
,by  having  the  upper  part  of  the  draft-tube  cylindrical  and  of 
small  diameter  and  beginning  the  conical  part  at  a  point  near 
enough  to  the  tailwater  level  to  insure  the  proper  action  of  the 
draft-tube. 

When  a  draft-tube  is  used  in  connection  with  a  turbine  set 
in  an  open  turbine-chamber,  then  the  height  of  the  draft-head  is 
limited  by  the  depth  of  the  water  above  the  turbine.  As  has 
already  been  stated  under  "  Turbines  for  Low  Heads,"  a  certain 
minimum  depth  of  water  above  the  guide-buckets  is  required 
to  prevent  the  air  from  being  sucked  through  the  turbine.  It 
will  readily  be  seen  that  the  use  of  a  draft-tube  not  only  increases 
the  speed  with  which  the  water  enters  the  guide-buckets,  but 
that  the  tendency  of  the  water  to  form  funnels  and  of  the  air- 
to  be  sucked  through  the  turbine  is  very  much  increased,  and  to 
offset  this  tendency  it  is  necessary  to  have  a  proportionally  greater 
depth  of  water  above  the  guide-buckets.  It  may  therefore  be 
stated  that  a  turbine  set  in  an  open  chamber  and  using  a  draft- 
tube  should  have  a  depth  of  water  above  the  highest  point  of 


ACCESSORIES  TO  TURBINES.  131 

the  discharge  rim  of  the  guide-bucket  ring  at  least  equal  to  one 
half  the  total  effective  head  (H)  acting  on  the  turbine.1 

When  a  very  high  draft-head  is  employed,  especially  in  con- 
nection with  large  draft- tubes,  the  water  has  a  tendency  to  pulsate 
or  oscillate  in  the  draft-tube,  and  if  the  turbine  is  subject  to  sud- 
den changes  in  load  and  provided  with  a  quick-acting  governor, 
the  pulsations  will  increase  to  such  an  extent  that  they  not  only 
have  the  effect  of  a  varying  draft-head  acting  on  the  turbine, 
and  thus  be  detrimental  to  good  speed  regulation,  but  these  pul- 
sations may  even  wreck  the  turbine.  With  the  turbine-gate 
closing  quickly,  the  momentum  of  the  water-column  in  the  draft- 
tube  will  cause  that  column  to  break,  creating  a  vacuum,  but 
as  soon  as  the  momentum  has  been  arrested,  the  atmospheric 
pressure  will  throw  the  water-column  upward  again,  striking  the 
turbine-runner  with  great  force. 

It  should  be  stated  here  that  conical  draft-tubes  are  less  liable 
to  pulsations,  and  can  therefore  be  employed  with  greater  draft- 
heads,  than  cylindrical  draft-tubes.  Conical  draft-tubes  are  also 
better  able  than  cylindrical  ones  to  expel  the  air  and  form  the 
draft  when  the  turbines  are  started  and  to  retain  the  draft  when 
the  turbines  are  running  with  light  loads. 

In  a  large  and  long  draft-tube,  when  the  turbine  is  started 
with  the  draft-tube  filled  with  air,  or  when  running  with  only  a 
small  fraction  of  the  full  load,  the  water  is  liable  to  crowd  to  one 
side  and  tumble  or  drop  through  the  draft-tube  without  expelling 
the  air  or  forming  a  suction,  and  the  draft-head  is  thus  lost.  Curved 
or  inclined  draft-tubes  are  more  likely  to  act  in  this  manner  than 
vertical  draft-tubes.  It  is  very  probable  that  many  turbines 
may  be  found  running  with  their  draft-tubes  partly  filled  with 
air,  and  thus  losing  the  entire  draft-head  without  the  fact  being 
known  to  the  parties  in  charge  of  the  plant. 

Gates  for  closing  the  lower  end  of  the  draft-tube  and  used 
for  filling  them  with  water  before  starting  the  turbines,  or  for 
reducing  the  discharge  area  when  working  with  part  load,  have 
been  used  to  some  extent  in  Europe,  but  they  are  expensive  and 
ponderous  for  large  turbines,  and  it  is  not  probable  that  they 
will  be  adopted  in  America. 

1  Mueller.     Francis-Turbinen,  p.  12. 


132  MODERN  TURBINE  PRACTICE. 

The  dip,  or  the  distance  to  which  a  vertical  draft-tube  reaches 
below  the  level  of  the  tail- water,  should  be  6  ins.  to  12  ins.  for 
short  and  small  draft-tubes,  increasing  to  20  ins.  to  24  ins.  for 
lorig  and  large  draft-tubes.  In  general,  it  may  be  said  that  a 
greater  dip  permits  a  greater  draft-head. 

Tfye  object  of  the  dip  is,  of  course,  to  seal  the  draft-tube  against 
the  inrush  of  air.  This  water  seal  is  of  importance,  especially 
while  the  turbine  is  started  and  the  draft  formed,  and  -it  is  there- 
fore essential  that  the  draft-tube  reaches  below  the  water  level 
at  all  stages  of  the  tail  water. 

To  facilitate  the  escape  of  the  water  from  a  vertical  draft- 
tube,  it  is  advisable  to  curve  the  lower  end  of  the  walls  of  the  tube 
outward  in  a  trumpet  shape,  as  shown  in  Fig.  38.  An  inclined 
or  curved  draft-tube  having  a  discharge  in  a  direction  consider- 
ably off  the  vertical,  or  in  a  horizontal  direction,  should  be  espe- 
cially protected  against  the  inrush  of  air  by  having  a  scoop- 
shaped  projection  at  its  discharge  end,  formed  by  extending  the 
upper  side  or  wall  of  the  draft-tube,  as  shown  in  Fig.  24. 

The  draft-tube  should  be  strong  enough  to  withstand  the  atmos- 
pheric pressure  to  which  it  is  subjected,  and  which  tends  to  collapse 
the  draft-tube.  The  pressure,  p,  in  pounds  per  square  inch,  at 
any  vertical  distance,  d,  in  feet,  above  the  tailwater  is  equal  to 

14  72 
p=.    '     xd,  but  can,-  of  course,  never  exceed  the  pressure  of  the 

o4 

atmosphere,  or  14.72  Ibs. 

Draft-tubes  are  usually  made  of  steel  plate,  with  lap-riveted 
telescoping  courses,  and  must  be  thoroughly  air-tight,  as  any  leak- 
age of  air  into  the  draft-tube  will  destroy  the  vacuum  and  cause 
the  loss  of  the  draft-head.  Draft- tubes  are  nearly  always  round 
in  cross-section,  as  this  form  is  the  most  convenient  to  manu- 
facture and  to  make  tight,  and  offers  the  greatest  resistance  against 
collapse.  Where  a  concrete  substructure  is  used  for  the  power- 
house, it  will  often  be  found  economical  both  in  first  cost  and 
maintenance,  to  dispense  with  a  metal  tube  altogether  and  to 
mold  the  draft-tube  directly  in  the  concrete  of  the  substructure. 

Stop-valves  for  Turbines. — When  it  is  desired  to  shut  down 
or  stop  a  turbine  unit  without  the  use  of  the  head-gate  it  is  the 
common  practice  to  close  the  regulating-gates.  However,  this 


ACCESSORIES  TO  TURBINES.  133 

method  will  not  permit  the  turbine  to  be  taken  apart  or  repaired, 
and  in  connection  with  high  heads  the  regulating-gates  are  rarely 
tight  enough  to  bring  the  turbine  to  a  standstill.  It  is  therefore 
advisable  to  have  a  separate  stop-valve  in  the  supply-pipe  near 
the  turbine,  by  which  means  the  water  may  be  quickly  shut  off 
and  the  turbine  stopped,  even  if  some  accident  or  the  accumula- 
tion of  ice  make  the  closing  of  the  head-gate  impossible.  Where 
more  than  one  turbine  unit  is  connected  to  the  same  penstock, 
such  stop-valves  are  essential,  as  otherwise  the  necessity  of  re- 
pairing one  unit  would  require  the  stopping  of  all  the  units  con- 
nected to  the  same  penstock. 

The  opening  and  closing  of  such  stop-valves  should  be  suffi- 
ciently slow  to  permit  the  water  to  change  its  velocity  without 
greatly  decreasing  or  increasing  the  pressure  in  the  penstock. 

In  America  the  stop-valves  employed  for  turbines  are  nearly 
always  gate-valves.  The  smaller  sizes  of  such  valves,  especially 
when  used  hi  connection  with  low  heads,  are,  as  a  rule,  provided 
with  a  screw-spindle  and  operated  by  hand.  Large  gate-valves, 
especially  when  used  hi  connection  with  high  heads,  require  so 
great  a  power  to  operate  them  quickly  that  it  becomes  necessary 
to  have  some  kind  of  motor  for  this  purpose  capable  of  furnishing 
a  large  power  for  a  short  space  of  time. 

In  some  water-power  electric  plants  an  electric  motor  is  used, 
geared  to  the  screw-spindle  of  the  valve.  This,  however,  requires 
a  very  large  motor  and  involves  either  the  installation  of  a  storage- 
battery  or  the  use  of  current  from  some  outside  source  to  be 
able  to  start  a  unit  when  the  whole  plant  is  shut  down. 

More  frequently  used  is  a  hydraulic  lift  mounted  above  the 
gate-valve  and  having  its  piston-rod  coupled  directly  to  the  valve- 
spindle,  as  shown  in  Figs.  31  and  46.  Where  the  head  employed 
is  high  enough,  the  pressure  water  may  be  taken  directly  from 
the  penstock,  but  for  lower  heads  a  pressure-pump  and  weighted 
accumulator  are  required,  and  in  this  case  oil  or  a  mixture  of  gly- 
cerine and  alcohol  is  frequently  used  as  a  pressure  fluid  instead 
of  water.  An  accumulator  consisting  of  a  closed  tank  or  receiver 
partly  filled  with  water,  which  is  subjected  to  air-pressure,  is  not 
to  be  recommended  for  this  purpose. 

The  use  of  air  instead  of  a  liquid  in  the  operating  cylinder 


134  MODERN  TURBINE  PRACTICE. 

of  a  gate-valve  is  not  advisable,  as  owing  to  differences  in  re- 
sistance encountered  at  different  parts  of  the  valve  travel,  the  valve 
may  alternately  stick  and  jump  forward,  and  is  thus  likely  to  pro- 
duce serious  shocks  in  the  penstock,  due  to  the  sudden  changes 
in  the  clear  passage  area  of  the  valve.  For  the  same  reason  a 
back  pressure  should  always  be  maintained  against  the  lower 
side  of  the  piston  when  the  gate  moves  downward,  to  prevent  it 
from  dropping  by  its  own  weight. 

A  by-pass  valve  is  often  employed  in  connection  with  a  gate- 
valve,  but  even  if  of  proportionately  large  size  it  can  only  partly 
balance  the  pressure  against  the  main-valve  disk,  owing  to  the 
leakage  through  the  regulating-gates. 

The  gate-valve  has  the  advantage  to  present  a  clear  passage 
area  to  the  flow  of  the  water,  and  if  in  good  condition,  to  be  per- 
fectly tight,. but  it  requires  a  great  amount  of  power  to  operate 
it  and  its  first  cost  is  very  high. 

In  Europe  the  stop-valves  employed  are  nearly  always  wing- 
gates,  operated  by  hand  by  means  of  a  worm-gear  and  worm,  as 
shown  in  Figs.  22  and  23  and  36  to  38. 

The  wing-gate  is  practically  balanced  in  all  positions,  thus 
requiring  little  power  to  operate  it,  and  its  first  cost  is  low;  but 
the  .passage  area  for  the  water  is  always  obstructed  by  the  wing 
and  it  is  impracticable  to  make  it  perfectly  tight.  No  tests  seem  to 
have  been  made  to  ascertain  what  amount  of  resistance  the  wing 
offers  to  the  flow  of  the  water. 

In  a  few  instances,  where  the  turbine  units  are  connected  to 
the  penstock  by  elbows  of  short  radius,  angle  stop-valves  have 
been  employed,  the  water  passage  area  being  the  annular  space 
between  the  outside  of  the  valve-disk  and  the  inside  of  the  valve- 
body. 

In  cold  weather  the  shutting  down  of  a  plant  over  night  or 
over  Sunday  should  be  effected  by  means  of  the  head-gates  and 
the  penstock  emptied  of  water,  as  the  water  when  stationary 
might  freeze  solid  and  destroy  the  penstock. 

Throttling-gates  for  Speed  Regulation. — To  regulate  the  speed 
of  turbines  by  means  of  throttling  the  water,  either  in  the  penstock 
above  or  in  the  draft-tube  below  the  turbine,  is,  next  to  the  by-pass 
regulation,  the  most  wasteful  arrangement  possible,  as  has  already 


FIGS.  57  and  58. — 6000-H.P.  Turbine  for  the  Shawinigan  \Vater  and  1 
diam.  of  runner   <?  *"   \  in.;  diam.  of  penstock,  11  ft.;   cubic 


\)wer  Co  ,  Shawinigan  Falls,    Que.     (Height  of  head,  125  ft.;    rev.  per  min.,  180: 
feet  of  water  per  sec.,  578;  vanes  ir.    ^aide-ring,  36;  va^  s  in  runner,  32. 

[To  face  page  135. 


ACCESSORIES  TO  TURBINES.  135 

been  stated  in  connection  with  the  European  practice,  and  this 
method  should  never  be  employed. 

The  large  turbine  units  installed  in  the  main  power-house  of 
the  Shawinigan  Water  and  Power  Co.,  at  Shawinigan  Falls,  Que., 
and  shown  in  Figs.  57  and  58,  are  regulated  in  this  manner,  having 
two  wing-  or  throttling-gates  inside  of  the  discharge-opening  of 
the  draft-tee  or  at  the  upper  end  of  the  draft-tube,  and  as  the 
plant  is  of  considerable  importance  and  the  turbines  are  some 
of  the  most  powerful  that  have  been  built  up  to  the  present  time, 
it  would  be  well  here  to  consider  the  matter  at  some  length. 

According  to  Mr.  W.  C.  Johnson,  chief  engineer  of  the  Sha- 
winigan Water  and  Power  Co.,  each  unit  consists  of  a  pair  of  radial 
inward-flow  reaction  turbines  on  horizontal  shaft,  and  develops 
6000  effective  H.P.,  under  125  ft.  head,  and  at  180  revolutions 
per  minute,  using  576  cu.  ft.  of  water  per  second,  and  therefore 
having  an  efficiency  of  73.6%,  when  working  with  full  capacity; 
but  this  figure  is  very  low  for  such  a  turbine,  and  an  efficiency 
of  about  78%  will  probably  be  obtained  in  practice.  Taking 
here  a  mean  of  75%  as  the  efficiency  of  the  turbines  when  develop- 
ing their  full  power  we  have: 

Turbine  working  with  full  capacity  and  using  565  cu.  ft.  of 
water  per  second:  Head  125  ft.,  effective  horse-power  6000, 
efficiency  75%. 

Turbine  using  75%  of  the  water  passed  at  full  capacity,  or 
424  cu.  ft. :  Effective  head  70.3  ft.,  head  destroyed  by  throttling- 
gates  54.7  ft.,  effective  horse-power  2160,  efficiency  corresponding 
to  125-ft.  head  36%,  while  register  or  wicket  gates  would  utilize 
the  whole  head  of  125  ft.  and  give  an  efficiency  of  about  78%. 

Turbine  using  50%  of  the  water  passed  at  full  capacity,  or 
283  cu.  ft.:  Effective  head  31.25  ft.,  head  destroyed  by  throttling- 
gates  93.75  ft.,  effective  horse-power  zero,  efficiency  correspond- 
ing to  125-ft.  head,  zero,  while  register  or  wicket  gates  would  utilize 
the  whole  head  of  125  ft.  and  give  an  efficiency  of  about  72%. 

At  first  sight  it  seems  absurd  that  a  turbine  using  one  half 
of  the  water  that  is  required  to  give  its  full  power  should  develop 
no  power  at  all,  but  a  few  simple  considerations  will  show  this 
to  be  the  case.1 

1  Meissner.     Hydraulische  Motoren,  vol.  2,  pp.  215  and  221. 


136  MODERN  TURBINE  PRACTICE. 

To  begin  with,  it  should  be  stated  that  the  size  of  the  passage 
area  of  the  guide-  and  runner-buckets  is  not  changed  by  the  posi- 
tion of  the  throttling-gates,  and  with  half  of  the  amount  of  water 
that  is  used  at  full  load  flowing  through  the  buckets,  the  speed 
of  the  water  in  the  buckets  will  also  be  only  one  half  and  the  head 
corresponding  to  that  velocity  will  be 

„     (0.5c)2 

~~ 


or  one  quarter  of  the  total  head;  the  remaining  three  quarters 
of  the  head  must  be  destroyed  by  the  throttling-gates. 

It  will,  therefore,  at  once  be  seen  that  the  throttling-gate 
regulates  the  speed  of  a  turbine  by  artificially  changing  the  effective 
head,  and  these  changes  can  only  be  in  a  downward  direction,  or 
by  decreasing  the  head. 

As  a  matter  of  fact,  the  same  efficiency  as  obtained  by  throttling- 
gates  can  be  had  by  regulating  the  turbines  by  means  of  the  head- 
gates  or  tailrace  gates,  or  by  variable  obstructions  hi  the  pen- 
stocks or  draft-tubes,  which  latter,  in  fact,  throttling-gates  are. 

It  will  also  be  seen  that  the  turbine  working  under  one  quarter 
of  the  total  head,  and  with  only  one  half  of  the  full  amount  of 
water,  will  give  one  eighth  of  the  full  power,  or,  in  this  case,  750  H.P., 
provided  the  turbine  is  allowed  to  run  at  the  speed  corresponding 
to  one  quarter  of  the  total  head,  that  is,  at  one  half  of  its  normal 
speed.  However,  when  the  speed  of  the  turbine  has  to  be  kept 
normal,  as  required  in  almost  every  plant,  especially  when  directly 
connected  to  an  alternating  dynamo,  as  in  this  instance,  the  water 
when  flowing  through  the  turbine  at  one  half  its  proper  speed 
will  have  no  opportunity  to  do  work  in  the  turbine,  but  will  drop 
freely  through  the  runner-buckets. 

This  may  be  better  understood  if  it  is  remembered  that  a 
turbine,  no  matter  whether  of  the  reaction  or  free  deviation  type, 
gives  the  best  efficiency  —  and  is  therefore  made  to  run  —  at 
about  one  half  of  the  maximum  velocity,  due  to  the  head,  or, 
in  other  words,  a  turbine  allowed  to  revolve  freely  will  run  with 
twice  the  velocity  at  which  it  gives  the  best  efficiency;  but  the 
turbine  can  develop  no  power  when  running  at  the  maximum 


ACCESSORIES  TO  TURBINES.  137 

speed  due  to  the  head,  as  the  runner-buckets  move  with  the  same 
velocity  as  the  water  and  the  water  therefore  can  exert  no  pres- 
sure upon  the  runner-buckets. 

These  considerations  will  show  that  a  turbine  having  a  con- 
stant passage  area  of  the  buckets  and  running  with  a  constant 
speed  can  develop  no  power  when  only  one  half  of  the  full  amount 
of  water  flows  through  the  turbine,  as  the  velocity  of  the  water 
will  also  be  only  one  half  of  the  speed  at  full  capacity  or  the  speed 
of  the  turbine,  remaining  constant,  will  be  twice  as  fast,  relative 
to  the  water. 

The  turbines  here  considered  will  therefore,  when  running  at 
normal  speed  but  without  any  load  except  then*  own  friction 
and  the  friction  of  the  dynamos,  directly  coupled  to  the  turbines, 
each  require  over  283  cu.  ft.  of  water  per  second,  or  more  than 
the  amount  required  to  develop  3000  H.P. 

The  whig-  or  throttling-gates  are  controlled  by  a  hydraulic 
governor.  The  guide-  and  runner-buckets  of  the  turbines  are  divided 
by  a  third  crown  into  two  unequal  parts,  and  ring  or  cylinder 
gates,  not  shown  in  the  figures,  operated  by  an  electric  motor 
controlled  from  the  switchboard,  are  provided  outside  of  the 
guide- wheels.  With  these  ring  gates  the  smaller  part  of  the 
guide-wheels  can  be  closed  and  the  turbine  will  then  develop 
4500  H.P.,  with  practically  full-gate  efficiency,  the  arrarrange- 
ment  being  about  the  same  as  having  two  turbine  units,  the  smaller 
one  being  shut  down  when  the  larger  one  alone  is  sufficient  to 
carry  the  load,  but  the  effect  of  the  regulating-  or  throttling-gates 
on  the  efficiency  is  the  same,  except  that  when  the  ring  gates  are 
partly  closed  the  throttling-gates  are  applied  to  a  4500-H.P.  tur- 
bine. 

The  turbine-units  can  be  shut  down  by  fully  closing  the  ring 
gates,  the  latter  thus  serving  also  as  stop-valves. 

Gages. — In  nearly  all  modern  engine-rooms  of  any  impor- 
tance will  be  found  gages  indicating  the  pressure  in  the  steam- 
chest,  receiver,  and  condenser,  and  similar  gages  used  in  connec- 
tion with  turbines  enclosed  in  cases  would  be  of  immense  value 
both  to  superintendents  in  charge  of  water-power  plants,  as  show- 
ing them  at  once  if  the  turbines  are  working  properly,  and  to 
the  hydraulic-power  engineers  and  the  turbine-builders,  as  giving 


138  MODERN  TURBINE  PRACTICE. 

•<& 

them  valuable  information  concerning  the  proper  proportions  and 
arrangement  of  the  different  parts  forming  an  installation. 

Of  such  gages  a  pressure-gage,  indicating  the  pressure  of  the 
water  near  the  entrance  of  the  guide-buckets,  and  a  vacuum-gage, 
indicating  the  amount  of  draft  or  suction  near  the  discharge-open- 
ings of  the  runner-buckets,  would  be  the  most  important. 

There  should  also  be  a  gage  showing  the  pressure  between  the 
runner-disk  and  the  head  of  the  case  or  the  dome,  and  turbines 
having  a  thrust-chamber  or  thrust-piston  should  have  a  gage 
showing  the  pressure  in  this  chamber  or  behind  the  piston. 

At  the  lower  end  of  a  long  penstock  should  be  a  gage  indi- 
cating water-hammer  and  the  rise  and  fall  of  pressure  due  to  the 
speed  regulation  of  the  turbine. 

A  tachometer,  or  gage,  showing  at  any  moment  at  what  rate 
of  speed  the  turbine  is  running,  and  a  dial  with  pointer  indicating 
the  gate-opening  or  position  of  the  speed-regulating  gates,  will 
also  be  found  of  advantage. 


CHAPTER  VII. 
GOVERNORS  AND  SPEED  REGULATION.1 

THE  greatest  difficulty  encountered  by  the  hydraulic-power 
engineer  is  the  speed  regulation  of  turbines  under  variable  loads, 
and  it  has  only  been  during  the  last  few  years  that  engineers  have 
been  able  to  regulate  the  speed  of  turbines  supplied  by  long  pen- 
stocks as  closely  as  is  common  in  steam-engineering  practice. 
The  reason  for  this  will  easily  be  seen  if  the  conditions  of  the 
steam-engine  and  turbine  regulations  are  compared. 

Steam  of  150  Ibs.  gage  pressure  weighs  about  0.37  Ib.  per 
cubic  foot,  and  the  supply-pipe  is  seldom  over  100  ft.  long,  so 
that  the  weight  of  the  moving  column  of  steam  will  rarely  exceed 
100  Ibs.,  while  the  velocity  is  about  100  ft.  per  second.  On  the 
other  hand,  water  weighs  62.3  Ibs.  per  cubic  foot  and  the  penstock 
may  be  1000  or  even  10,000  ft.  long,  so  that  the  weight  of  the 
moving  column  of  water  may  be  millions  of  pounds,  while  the 
velocity  is  rarely  over  10  ft.  per  second.  Thus  the  energy  repre- 
sented by  the  moving  water-column  may  be  hundreds  or  even 
thousands  of  times  the  energy  represented  by  the  moving  steam- 
column. 

Every  change  of  load  or  power  developed  requires  a  change 
in  the  engine  cut-off  or  in  the  gate-opening,  of  the  turbine,  and 
this  in  turn  requires  a  change  in  the  velocity  of  flow  in  the  supply- 
pipe  or  penstock,  which  means  a  change  in  the  amount  of  energy 
represented  by  the  moving  column. 

1  For  the  principles  involved  in  the  speed  regulation  of  turbines  see  "Ele- 
ments of  Design  Favorable  to  Speed  Regulation  in  Plants  Driven  by  Water 
Power,"  by  Allan  V.  Garratt,  printed  in  the  appendix  to  this  book;  also  "Speed 
Government  in  Water-power  Plants,"  by  Mark  A.  Replogle,  Journal  of  the 
Franklin  Institute,  Feb.  1898,  p.  81. 

139 


140  MODERN  TURBINE  PRACTICE. 

Steam  is  compressible  and  elastic,  and  if  the  load  of  the  engine> 
and  thus  the  velocity  required  in  the  supply-pipe,  is  suddenly 
decreased,  the  excess  of  energy  in  the  moving  steam-column  is 
absorbed  by  the  compression  of  the  steam  contained  in  that 
column,  while  if  the  load  and  the  required  velocity  in  the  pipe  is 
suddenly  increased  the  lack  of  energy  is  supplied  by  the  expansion 
of  the  steam  contained  in  the  moving  column.  Both  the  absorp- 
tion and  the  supply  of  energy  are  required  only  for  a  very  short 
time,  as  owing  to  the  small  inertia  of  the  steam-column  the  change 
in  velocity  is  quickly  attained.  Water  is  incompressible  and 
inelastic,  and  if  the  load  of  the  turbine,  and  thus  the  velocity  re- 
quired in  the  penstock,  is  suddenly  decreased,  the  excess  of  energy 
in  the  moving  column  must  find  some  outlet,  otherwise  either  the 
penstock  or  the  turbine  will  be  wrecked,  while  if  the  load  and  the 
required  velocity  in  the  penstock  is  suddenly  increased  the  lack 
of  energy  must  be  supplied  from  some  outside  source.  Both  the 
escape  and  the  supply  of  energy  are  required  for  a  much  longer 
time  than  in  the  case  of  steam,  as  owing  to  the  great  inertia  of 
the  water-column,  the  change  in  velocity  can  only  be  slowly 
attained. 

Any  decrease  in  the  gate-opening  and  consequent  decrease  in 
the  velocity  of  the  water  in  the  penstock  will  thus  produce  a  tem- 
porary increase  in  the  penstock  pressure,  and  with  the  gates  clos- 
ing quickly,  this  increase  in  pressure  may  rise  to  the  force  and 
suddenness  of  a  blow,  usually  called  water-hammer.  On  the  other 
hand,  any  increase  in  the  gate-opening  and  in  the  velocity  of  the 
water  in  the  penstock  will  produce  a  temporary  decrease  in  the 
penstock  pressure.  Such  changes  in  gate-opening  will  frequently 
cause  long-drawn-out  pulsations  in  the  penstock  pressure  or  surging 
of  the  water,  and  this  action  is  often  favored  by  badly  arranged 
penstocks,  relief-valve?,  stand-pipes,  air-chambers,  and  connections, 
and  aided  by  wave-motion  and  eddies  in  the  headrace  near  the 
penstock  entrance.  It  is  evident  that  the  increase  and  decrease 
in  the  penstock  pressure,  water-hammes,  and  the  surging  of  the 
water,  being  in  effect  the  same  as  varying  heads  acting  on  the 
turbine,  must  have  a  detrimental  influence  on  the  speed  regulation 
of  the  turbine. 

To  obtain  a  good  speed  regulation  it  is  often  necessary,  espe- 


GOVERNORS  AND  SPEED  REGULATION.  141 

cially  in  connection  with  turbines  supplied  by  long  penstocks,  to 
use  some  auxiliary  device  or  devices  for  the  escape  and  supply  of 
energy  or  for  the  escape  at  least,  which  may  be  briefly  considered 
in  the  following: 

The  pressure-relief  valve  serves  for  the  escape  of  energy,  when 
the  pressure  rises  beyond  a  certain  limit,  in  exactly  the  same 
manner  as  the  safety-valve  of  a  boiler.  Relief-valves  are  well 
known,  but  nearly  all  of  them  are  of  poor  design,  being  held  closed 
by  a  single  short  helical  spring  of  a  few  turns,  and  therefore  can 
open  only  to  a  very  small  extent.  A  good  spring  relief -valve 
should  have  3  to  6  helical  springs,  according  to  the  size  of  the 
valve,  and  these  springs  should  be  long  and  have  many  turns,  so 
as  to  permit  the  valve  to  open  sufficiently,  without  requiring  too 
great  a  rise  in  pressure  in  the  penstock.  Provision  should  be  made 
for  ascertaining  at  any  time  whether  the  valve  is  in  working  con- 
dition and  set  for  the  proper  pressure.  This  can  usually  be  done 
by  a  lever-and-chain  attachment  for  pulling  the  valve  open  or  by 
slackening  the  springs,  while  the  valve  is  under  water-pressure, 
until  the  valve  blows  off,  and  to  avoid  the  drenching  of  the  man 
testing  the  valve,  the  latter  should  be  enclosed  like  the  pop  safety- 
valves  for  boilers. 

The  Lombard  pressure-relief  valve,  shown  diagrammatically 
in  Fig.  59,  is  a  great  improvement  over  the  ordinary  relief-valve. 
Its  action  is  as  follows:  A  is  the  end  of  a  penstock  or  a  nozzle  of 
a  penstock  in  which  the  pressure  is  to  be  relieved  when  a  certain 
limit  has  been  reached.  The  disk  of  the  relief- valve  c  is  held  to 
its  seat  against  the  water-pressure  in  the  penstock  by  the  water- 
pressure  behind  the  piston  e,  the  pressure-water  behind  the  piston 
being  supplied  from  the  penstock  through  pipe  /.  As  the  pres- 
sures per  unit  area  against  the  valve-disk  and  behind  the  piston 
are  equal,  the  piston  is  made  larger  in  diameter  than  the  disk,  so 
that  the  total  pressure  behind  the  piston  will  not  only  overcome 
the  total  pressure  against  the  valve-disk,  but  also  hold  the  latter 
firmly  to  its  seat.  The  space  behind  the  piston  e  is  also  connected 
through  pipe  i  to  the  waste-valve  D.  This  is  a  balanced  valve 
held  closed  by  means  of  the  spring  p,  while  the  water-pressure  in 
the  penstock,  communicated  through  pipe  r  and  acting  behind 
the  piston  n,  tends  to  open  the  waste- valve.  The  force  of  the 


142 


MODERN  TURBINE    PRACTICE. 


spring  p  can  be  regulated  so  that  the  water-pressure  will  overcome 
the  force  of  the  spring  and  open  the  valve  at  any  desired  pressure 
in  the  penstock. 


FIG.  59. — Lombard  Pressure-relief  Valve.     Made  by  The  Lombard 
Governor  Co.,  Boston,  Mass. 

With  the  relief-valve  closed    and    the  water-pressure  in  the 
penstock  rising  above  the  normal  to  the  pressure  for  which  the 


GOVERNORS  AND  SPEED  REGULATION.  143 

spring  p  is  set,  the  piston  n  will  open  the  waste-valve,  which  will 
relieve  the  pressure  behind  the  relief-valve  piston  e  and  allow 
the  pressure-water  to  escape.  While  water  will  begin  to  flow 
through  pipe  /  as  soon  as  the  waste-valve  is  opened,  yet  the  area 
of  pipe  /  is  so  much  smaller  than  the  area  of  pipe  i  and  the  waste- 
valve  opening,  that  the  pressure  behind  the  piston  e  will  at  once 
fall  below  the  pressure  which  exists  in  the  penstock,  and  therefore 
the  pressure  hi  the  penstock  forces  the  relief-valve  disk  c  and 
piston  e  back,  or,  in  other  words,  opens  the  relief-valve. 

The  greater  the  rise  in  pressure  is  in  the  penstock  the  greater 
will  be  the  extent  to  which  the  waste-valve  opens,  and  conse- 
quently the  greater  will  be  the  reduction  in  pressure  behind  the 
piston  e,  and  therefore  the  greater  the  extent  to  which  the  relief- 
valve  opens. 

As  soon  as  the  pressure  in  the  penstock  has  fallen  to  the  pressure 
for  which  the  spring  p  is  set,  the  latter  closes  the  waste-valve,  the 
pipe  /  restores  the  full  penstock  pressure  behind  the  piston  e,  and 
the  latter  closes  the  relief-valve.  To  prevent  any  surging  in  the 
penstock,  due  to  the  closing  of  the  relief-valve  and  the  consequent 
retardation  of  the  water,  the  relief-valve  is  made  to  close  slowly, 
the  rate  of  closing  being  adjustable  by  means  of  the  valve  h. 

Relief-valves  must  be  prevented  from  freezing  or  from  becoming 
incrusted  with  ice,  as  otherwise  they  may  be  rendered  entirely 
useless. 

The  by-pass,  which  may  be  employed  where  economy  in  water 
consumption  is  not  demanded,  consists  of  a  valve  or  gate  of 
sufficient  area  to  pass  the  entire  volume  of  water  required  by  the 
turbine  at  full-gate  opening  and  moved  hi  conjunction  with  the 
speed-regulating  gates.  With  the  turbine-gate  fully  open,  the 
by-pass  is  closed,  but  when  the  regulating-gates  commence  to 
close,  the  by-pass  opens  and  its  passage  area  is  increased  in  the  same 
proportion  as  the  gate-opening  decreases,  so  that  the  combined 
area  of  the  gate-opening  and  the  by-pass  is  always  sufficient  to 
pass  the  entire  volume  of  water  required  by  the  turbine  at  full- 
gate  opening;  thus  the  velocity  of  the  water  in  the  penstock  and 
the  amount  of  water  discharged  remains  always  the  same,  the 
discharge  of  the  by-pass  being  run  to  waste.  This  arrangement 
not  only  permits  the  closest  speed  regulation  with  violently  flue- 


144  MODERN  TURBINE  PRACTICE. 

tuating  loads,  but  also  relieves  the  penstock  from  shock  or  water- 
hammer,  and  is  therefore  often  used  in  connection  with  impulse 
turbines  working  under  high  heads  and  supplied  by  very  long 
penstocks. 

European  engineers  have  abandoned  the  ordinary  by-pass  on 
account  of  the  great  waste  of  water  which  its  use  implies,  but 
frequently  use  the  temporary  by-pass,  which  is  essentially  the 
same  device  as  the  ordinary  by-pass,  but  the  speed-regulating 
gates  or  their  rigging  and  the  by-pass  are  connected  by  means 
of  a  dash-pot  or  cataract.  The  temporary  by-pass  will  thus  open 
while  the  speed-regulating  gate  closes,  in  the  same  manner  as 
described  in  connection  with  the  ordinary  by-pass,  but  as  soon 
as  the  closing  movement  of  the  regulating-gate  ceases,  the  by-pass 
at  once  starts  automatically  to  slowly  close  again,  being  actuated 
by  a  spring,  counterweight,  or  hydraulic  pressure.  The  speed  with 
which  the  by-pass  closes  is  easily  regulated  by  changing  the  size 
of  the  aperture  connecting  the  two  ends  of  the  dash-pot.  The 
temporary  by-pass  does  not  open  at  all  when  the  regulating-gate 
closes  very  slowly.  It  will  be  seen  that  the  temporary  by-pass 
is  similar  in  its  effect  to  the  relief-valve,  except  that  the  by-pass 
opens  before  a  rise  in  the  penstock  pressure,  due  to  the  closing 
of  the  regulating-gates,  takes  place. 

The  temporary  by-pass  gives  full  protection  to  the  penstock 
and  permits  the  closest  speed  regulation  with  a  decreasing  load, 
but  cannot,  of  course,  assist  the  governor  to  prevent  slowing  down 
of  the  speed  when  the  load  on  the  turbine  is  increasing. 

A  by-pass  is  usually  located  outside  of  the  turbine- case,  so 
that  its  discharge  will  not  interfere  with  the  proper  working  of  the 
turbine  or  draft-tube. 

The  stand-pipe  is  frequently  employed  to  aid  the  governor 
and  thus  to  improve  the  speed  regulation  of  turbines,  and  is  simply 
an  open  reservoir  which,  to  a  limited  extent,  will  absorb  or  store 
energy,  when  the  gate-opening  is  decreased  in  consequence  of  a 
reduction  in  the  load  of  the  turbine  and  will  supply  energy  when 
the  gate-opening  is  increased  in  consequence  of  an  increase  hi 
the  load  of  the  turbine.  The  stand-pipe  is  the  best  possible  relief- 
valve  and  should  have  its  top  edge  a  few  feet  above  the  high-water 
level  in  the  headrace  and  its  diameter  or  capacity  should  be  in 


GOVERNORS  AND  SPEED  REGULATION.  145 

accordance  with  the  volume  of  water  discharged  by  the  turbine 
at  full-gate  opening  and  the  length  of  the  penstock. 

When  the  gate-opening  of  the  turbine  is  suddenly  reduced, 
the  excess  of  water  flows  into  the  stand-pipe,  causing  the  water 
therein  to  rise,  and  perhaps  to  escape  over  the  top  edge  of  it, 
until  the  water-column  in  the  penstock  has  slowed  down,  while 
when  the  gate-opening  is  suddenly  enlarged  the  additional  water 
required  is  supplied  from  the  stand-pipe,  causing  the  water  therein 
to  fall  until  the  speed  of  the  water-column  has  increased  to  meet 
the  demand.  In  connection  with  high  heads  stand-pipes  are 
rarely  used,  as  they  are  not  only  very  expensive  but  also  less  effective 
on  account  of  the  inertia  of  the  water-column  in  the  stand-pipe. 

Stand-pipes  must  be  carefully  protected  from  freezing,  as 
otherwise  they  may  be  rendered  entirely  useless.  A  waste-pipe 
should  be  provided  to  carry  off  the  water  escaping  over  the  top 
edge  of  the  stand-pipe. 

Air-chambers  are  often  used  on  penstocks,  but  while  they  may 
be  useful  to  protect  the  penstock  against  the  effects  of  water- 
hammer,  they  are  of  little  or  no  value  as  an  aid  to  the  regulation 
of  the  turbines.  To  cushion  the  shocks  in  a  penstock  an  air- 
chamber  should  be  of  ample  capacity,  and  as  air  is  readily  absorbed 
by  the  water,  an  air-pump  should  be  provided  to  replace  the  air 
thus  carried  off.  Gage-glasses  and  try-cocks  should  be  placed 
on  each  air-chamber,  so  that  it  may  at  once  be  seen  whether  it 
is  effective. 

The  blows  struck  by  water  in  a  penstock  or  water-hammer 
are  first  and  most  violently  felt  at  the  lower  end  of  the  penstock 
and  in  the  direction  in  which  the  water-column  moves,  and  from 
there  back  up,  so  to  say,  with  diminishing  strength  towards  the 
upper  end  of  the  penstock.  Therefore  all  such  safety  devices 
as  the  relief-valve,  by-pass,  stand-pipe,  and  air-chamber  should 
be  at  the  extreme  lower  end  of  the  penstock  and  their  discharge 
or  connection  should  be  in  the  direction  in  which  the  water-column 
moves.  A  stand-pipe  should  be  connected  with  the  penstock 
by  a  short,  straight  pipe  of  large  diameter  and  an  air-chamber 
by  a  short  neck,  also  of  large  diameter. 

The  fly-wheel  is  frequently  employed  in  Europe,  and  to  some 
extent  in  America,  to  aid  the  governor  and  thus  to  improve 


146  MODERN  TURBINE  PRACTICE. 

the  speed  regulation,  especially  in  connection  with  turbines  work- 
ing under  high  heads,  but  a  fly-wheel  cannot,  of  course,  protect 
a  penstock  against  water-hammer.  A  turbine-runner  has  very 
little  fly-wheel  capacity,  and  the  use  of  a  fly-wheel  will  therefore 
eliminate  the  small  variations  in  speed,  due  to  slight  but  sudden 
fluctuations  in  load,  to  water-hammer,  to  the  surging  of  the  water 
in  the  penstock  and  draft-tube,  and  to  other  causes,  which 
momentary  variations  even  the  best  governor  cannot  prevent. 
The  amount  of  energy  which  a  fly-wheel  can  absorb  or  give  out 
is  only  small,  but  it  will  at  least  retard  the  changes  in  speed  of 
the  turbine  with  changes  of  load.  Where  the  turbines  are  used 
to  drive  dynamos  sufficient  fly-wheel  capacity  may  be  given  to 
the  armature  or  revolving  field  to  make  a  separate  fly-wheel 
unnecessary.  This  plan  was  adopted  by  the  Niagara  Falls  Power 
Co.  for  its  5000-H.P.  alternating  machines. 


Turbine-gates,  owing  to  their  large  size  and  weight  and  the 
great  resistance  offered  by  the  water  and  by  friction,  require  a 
large  amount  of  power  for  their  movement,  and  for  this  reason 
cannot  be  actuated  directly  by  a  sensitive  centrifugal  governor. 
An  auxiliary  machine,  called  a  relay  or  servomotor,  and  con- 
trolled by  the  centrifugal  governor,  is  therefore  employed  to 
actuate  the  gates,  and  the  governor  is  called,  according  to  the 
form  of  power  used  in  the  relay,  a  mechanical  or  hydraulic 
governor. 

Mechanical  and  hydraulic  governors  of  good  design  both 
serve  their  purpose  equally  well,  but  a  hydraulic  governor  is 
usually  less  complicated  in  construction  than  a  mechanical  one. 
In  Europe,  governors  with  electrical  and  pneumatic  relays  have 
also  been  tried,  but  have  not  proven  a  success. 

A  governor  occasionally  used  for  small  turbines  is  the  brake- 
governor.  With  this  governor  the  speed-regulating  gate  remains 
fully  open  and  the  turbine  thus  always  develops  its  maximum 
power,  the  power  in  excess  over  the  demand  being  destroyed 
by  a  friction  resistance. 

A  modern  turbine  governor  consists  of  three  principal  parts, 
viz.:  the  centrifugal  governor,  which  may  be  of  any  approved 


GOVERNORS  AND  SPEED   REGULATION. 


147 


design;  the  relay,  using  either  mechanical  or  hydraulic  power 
and  controlled  by  the  centrifugal  governor,  and  the  return.1  When 
a  change  of  load  and  consequent  change  in  the  speed  of  a  tur- 
bine takes  place,  the  governor  will  set  the  regulating-gate  hi  motion, 
but  owing  to  the  inertia  of  the  water  a  certain  amount  of  time- 
is  required  for  the  turbine  to  return  to  the  proper  speed,  and  the 
regulating-gate  would  have  traveled  in  the  meantime  beyond  the 
required  position  and  would  have  to  start  at  once  in  the  opposite 
direction;  that  is,  the  turbine  would  be  overgoverned  or  racing 
if  the  return  were  not  used  to  arrest  the  motion  of  the  relay  and 
with  it  the  motion  of  the  regulating-gate  before  the  latter  has 
traveled  too  far. 

Of  great  importance  in  connection  with  turbine  governors  is. 
the  time  of  closing — that  is,  the  time  required  by  a  governor  to 
move  the  regulating-gate  from  the  fully  open  position  to  the  fully 
closed  position — as  it  will  easily  be  seen  that  the  quicker  the  governor 
moves  the  gate  the  closer  will  be  the  speed  regulation.  A  mechan- 
ical governor  will  usually  require  from  15  to  25  seconds  for  an 
entire  closing  movement  of  the  gate,  although  mechanical  governors, 
have  been  built  which  required  only  3  seconds.  With  hydraulic 
governors  the  time  of  closing  may  be  reduced  to  one  second,  and 
hydraulic  governors  will  therefore  give  the  closest  possible  speed 
regulation. 

To  show  the  performance  to  be  expected  from  a  modern  tur- 
bine governor,  it  may  be  stated  that  with  favorable  conditions, 
the  speed  may  be  kept  within  5  or  6%  of  the  normal  when  the 
full  load  is  suddenly  thrown  off  and  it  will  require  between  five 
to  fifteen  seconds  for  the  turbine  to  return  to  normal  speed.  With 
ordinary  electric-railway  loads,  speed  variations  of  about  3%  as 
a  maximum  may  be  expected.2 


1  The  reference  letters  given  in  Figs.  28,  32,  33,  48,  52,  and  66  to  69  have 
the  following  meanings :  C  is  the  centrifugal  governor,  M  is  the  relay,  S  is  the 
valve  actuated   by  the  centrifugal  governor  and  controlling  the  relay,  Z  is 
the  return,  and  R  is  the  connection  between  the  relay  and  the  regulating-gate. 

2  The  figures  here  given  are  taken  from  "Elements  of  Design  Favorable  to 
Speed  Regulation,"  etc.,  by  Allan  V.  Garratt,  printed  in  the  appendix  to4his, 
book. 


OWL  ENGINEERING 


(I.  ofC    , 

f  IRf>  .1  r 


148  MODERN  TURBINE  PRACTICE. 

The  mechanical  governor,  at  one  time  the  only  turbine  governor 
obtainable,  has  been  replaced  to  a  great  extent  by  the  hydraulic 
governor.  The  power  for  a  mechanical  governor  is  usually  taken 
from  the  turbine  which  it  regulates  and  is  transmitted  to  the 
gate  by  means  of  a  ratchet-wheel  and  pawls,  friction  gearing  or 
clutches. 

The  mechanical  governor  best  known  in  America  is  the  Re- 
plogle  governor.  The  centrifugal  governor  and  the  return  of  a 
Replogle  governor,  employing  electric  current  for  throwing  the 
relay  into  or  out  of  action,  is  shown  diagrammatically  in  Fig.  60 
and  may  be  described  as  follows:1 

In  Fig.  60,  Z  is  a  speed  governor;  A  is  a  vertically  sliding 
bracket  which  is  supported  by  cam  B;  S  is  a  toothed  segment 
operated  by  the  turbine-gate  shaft  G,  which  is  also  toothed; 
C  is  an  electric  contact-point  supported  by  a  lug  in  the  top  of  A ; 
O  is  a  smilar  contact  supported  by  a  bottom  lug;  L  is  the  lever 
tilted  by  the  governor-balls  when  a  variation  of  speed  occurs 
(it  serves  also  to  complete  the  battery  circuit  by  touching  con- 
tacts C  or  0  when  the  speed  varies) ;  D  is  a  binding-post  through 
which  the  battery  current  enters  the  lever  L. 

Bracket  A,  contacts  C  and  0,  lever  L,  cam  B,  segment  S,  which 
operates  the  cam,  and  gate-shaft  G  with  its  pinion  are  known 
as  the  relay  controlling  device,  and  assuming  the  turbine  to  be 
running  at  normal  speed  their  operation  may  be  explained  as 
follows :  If  additional  load  is  thrown  onto  the  turbine,  the  governor- 
balls  will  allow  lever  L  to  touch  contact  0  (which  must  be  con- 
nected by  a  wire  conductor  to  magnet  0.  It  is  assumed  that 
the  switch  E  is  closed).  Magnet  0  being  thus  energized,  trips 
the  auxiliary  machine  or  relay,  not  shown,  which  starts  to  open 
the  turbine-gates  by  turning  G  in  the  direction  of  the  arrow.  G  in 
turning  carries  the  segmental  rack  S  with  it,  which  lowers  cam  B, 
allowing  bracket  A,  consequently  contact  0,  to  drop  away  from 
lever  L,  breaking  the  electrical  circuit,  which  cuts  the  auxiliary 
power  out  of  action  and  stops  the  gate  motion  before  the  added 
power  has  given  any  increased  velocity  to  the  turbine.  If  the 


1  The  description  of  this  governor  was  kindly  furnished  by  Mr.  Mark  A. 
Heplogle. 


GOVERNORS  AND  SPEED  REGULATION. 

added  water  is  enough  to  carry  the  new  load  no  further  action 
of  the  governor  will  occur.  If  the  speed  continues  to  drop  this 
operation  will  be  repeated  until  the  speed  will  not  drop  farther. 


HI— 


BATTERY. 


FIG.  60. — Centrifugal  Governor  and  Return  of  Replogle  Governor.      Built 
by  The  Replogle  Governor  Works,  Akron,  Ohio. 

(It  must  be  remembered  that  the  lever  L  varies  its  position  with 
the  slightest  variations  in  speed.)  Since  the  contact  end  of  L 
is  now  maintained  hi  a  lower  position  it  follows  that  the  speed 
is  slightly  lower. 


150  MODERN  TURBINE  PRACTICE. 

There  are  two  reasons  for  this  complex  action  of  the  relay 
controlling  device:  (1)  The  effect  of  the  added  water  is  not  avail- 
able until  some  little  time  after  the  turbine-gates  are  opened. 
Therefore  it  is  necessary  to  stop  the  gate  motion  before  the  speed 
has  increased,  as  the  added  water  may  cause  too  great  an  increase 
in  speed,  which  will  cause  a  "see-sawing  "  or  racing  effect.  (2)  The 
momentum  or  fly-wheel  capacity  of  the  plant  must  always  carry 
the  added  load  until  the  new  power  is  furnished  by  the  water. 
In  order  to  draw  this  power  from  the  revolving  parts  their  speed 
must  be  dropped  enough  to  feed  out  the  proper  amount.  The 
cam  B  is  designed  or  made  steeper  or  flatter  so  as  to  feed  out 
exactly  the  proper  amount  of  power  in  opening  gate  or  to  absorb 
it  in  the  reverse  operation.  If  a  load  is  thrown  off  the  turbine 
the  operations  are  all  reversed.  This  allows  lever  L  to  have 
position  X  when  the  turbine  has  no  load  and  the  position  Y  when 
the  turbine  is  carrying  full  load.  This  variation  is  equal  to  from 
1  to  6%  in  speed,  depending  on  the  amount  of  momentum  or 
fly-wheel  effect  in  the  plant.  If  the  fly-wheel  effect  is  ample  a 
flat  cam  of  1%  variation  can  be  used.  If  1%  drop  in  speed  will 
not  feed  out  storage  power  enough  to  carry  the  load  until  gravity 
acts  then  a  larger  drop  must  be  resorted  to  or  the  result  will  be 
hunting  or  racing. 

In  a  later  mechanical  governor,  Replogle  has  added  another 
refinement  as  follows:  After  a  change  in  load  has  been  balanced 
by  the  above  principles,  a  set  of  springs  aided  by  a  cataract  cylinder 
gradually  returns  the  relay  controlling  apparatus  to  its  original 
central  position,  turning  on  or  off  water  slowly  until  the  speed 
is  exactly  normal  although  the  turbine-gate  sets  at  a  different 
position.  This  is  called  a  "Relay  Returning  Governor." 

A  still  later  governor  has  a  further  refinement  which  embraces 
all  of  the  actions  referred  to  above  and  an  additional  action  that 
gradually,  increases  the  speed  as  the  load  goes  on.1  With  this 
governor  it  is  possible  to  have  the  speed  automatically  increase 
from  normal  speed  to  as  much  as  10%,  from  no  load  to  full  load, 
and  }^et  all  of  the  previous  operations  have  taken  place  at  each 
change  in  load.  The  idea  of  this  over-returning-governor  is  to 

1  See  Engineering  News,  Nov.  13,  1902,  p.  4C9. 


GOVERNORS  AND  SPEED  REGULATION.  151 

make  up  for  line  losses  in  direct-current  transmission  or  to  offset 
belt  lag  when  belt  or  rope  drives  are  used.  This  same  governor 
can  operate  as  either  the  first  or  second  styles  mentioned  by 
simple  adjustments,  and  is  called  "Replogle's  Differential  Relay 
Governor." 

One  great  drawback  in  turbine-governing  is  that  sufficient  fly- 
wheel effect  is  not  always  furnished  in  the  plant  construction. 
Often  there  is  practically  none,  even  when  other  conditions  are 
bad,  requiring  a  governor  to  be  a  complex  machine. 

The  hydraulic  governor,  although  having  been  in  use  only  for 
a  few  years,  has  found  an  extensive  application.1  The  power 
of  a  hydraulic  governor  is  furnished  by  the  pressure  of  a  fluid 
acting  behind  a  piston  in  the  relay-cylinder.  The  pressure  fluid 
for  hydraulic  governors  used  in  connection  with  turbines  work- 
ing under  heads  of  about  200  ft.  or  more  is,  as  a  rule,  water  taken 
directly  from  the  penstock.  To  avoid  carrying  over  sand  or 
gritty  matter  from  the  penstock  to  the  relay,  which  would  cause 
rapid  wear  of  the  working  parts  of  the  relay,  the  water  con- 
nection for  the  latter  should  be  made  by  means  of  a  nozzle  of 
large  diameter  and  having  a  length  of  about  twice  the  diameter. 
This  nozzle  is  set  vertically  on  top  of  the  penstock,  in  a  location 
where  water-hammer  is  the  least  likely  to  affect  the  relay.  The 
nozzle  is  closed  at  the  end  by  a  head  or  blank  flange  and  the 
supply-pipe  for  the  relay  connected  to  the  centre  of  this  head 
or  blank  flange.  Thus  with  a  supply-pipe  2  ins.  in  diameter  and 
a  maximum  speed  of  water  in  this  pipe  of  4  ft.  per  second,  the 
upward  movement  of  the  water  in  a  nozzle  24  ins.  in  diameter 
would  never  be  greater  than  about  f  in.  per  second,  or  far  too 
small  to  carry  any  sand  or  gritty  matter  along  with  it. 

In  most  cases,  however,  it  will  be  found  advisable  to  pass  the 
pressure-water  used  in  a  hydraulic  relay  through  a  filter  or  fine 
screen  or  sieve  to  keep  out  any  light  or  floating  matter.  Two 
filters  or  screens  should  be  provided,  so  that  one  may  be  cleaned 
while  the  other  is  in  operation. 

A  simple  water-filter  is  shown  in  Figs.  61  and  62.     The  water 


1  The  hydraulic  governor  was  invented  in  1885  by  Piccard,  Pictet  &  Co. , 
'Geneva,  Switzerland. 


152  MODERN  TURBINE  PRACTICE. 

enters  the  filter  through  the  opening  E  and  leaves  through  the 
opening  S.  The  screen  drum  has  six  compartments,  of  which 
the  one  opposite  the  chamber  A  is  not  in  use  and  may  be  cleaned 
by  opening  the  valve  R,  which  causes  the  filtered  water  from 
the  interior  of  the  drum  to  flow  through  the  screen  in  the  reverse 
direction,  thus  washing  off  any  matter  clogging  the  screen.  By 
rotating  the  drum  one  screen  after  the  other  may  be  washed. 

The  interior  working  parts  of  a  relay  using  water  as  a  pressure- 
fluid  are  frequently  lined  with  brass  to  prevent  corrosion,  which 
latter  might  cause  the  relay  to  stick. 

Where  the  head  under  which  the  turbine  is  working  is  less 
than  about  200  ft.,  or  where  it  is  desirable  for  other  reasons,  the 


FIGS.  61  and  62. — Water-filter  for  Hydraulic  Governors.      Built  by  Escher, 
Wyss  &  Co.,  Zurich,  Switzerland. 

pressure-fluid  employed  for  the  hydraulic  governor  is  usually 
oil,  though  if  the  pressure-fluid  is  liable  to  be  exposed  to  freezing 
temperatures,  a  mixture  of  glycerine  and  alcohol  is  often  employed. 
The  oil  used  should  be  of  comparatively  high  viscosity,  absolutely 
non-corrosive,  have  a  low  freezing-point,  and  should  not  break 
down  into  vaseline  after  long  service. 

To  produce  the  necessary  pressure  an  oil  force-pump  is  required, 
and  to  equalize  the  supply  and  demand  of  oil  an  accumulator 
must  be  provided,  which  should  be  of  the  receiver  type,  that  is,  a 
closed  tank,  or  receiver,  partly  filled  with  oil,  which  is  subjected 
to  air-pressure.  A  weighted  accumulator  is  not  to  be  recommended 
on  account  of  the  inertia  of  the  weights.  Where  the  head  is 
sufficiently  high  the  accumulator  may  be  dispensed  with  by  sub- 
jecting the  oil  to  the  pressure  of  the  water  in  the  penstock. 

The  use  of  oil  as  pressure-fluid  has  the  advantage  that  the 
interior  working  parts  of  the  relay  require  no  separate  lubrication 
and  the  wear  of  these  parts  is  reduced  to  a  minimum.  With  the 


GOVERNORS  AND  SPEED  REGULATION.  153 

proper  kind  of  oil  the  same  pump  may  be  used  to  supply  the 
relay  and  to  furnish  a  forced  oil  lubrication  for  the  turbine  bear- 
ings; thus  the  oil  used  for  the  collar-bearing  of  the  turbine  shown 
in  Figs.  22  and  23  is  supplied  by  the  relay  pressure-pump. 

The  hydraulic  governor  best  known  in  America  is  the  Lombard 
governor.1  An  attachment  may  be  used  in  connection  with  the 
Lombard  governor,  by  which  the  speed  of  a  turbine  can  be  varied 
while  the  latter  is  running;  thus  a  turbine  driving  an  alternating 
dynamo  may  be  brought  up  to  speed  and  the  alternator  syn- 
chronized to  throw  it  into  parallel.  For  this  purpose  the  stem  of 
the  valve  controlling  the  relay  is  made  in  two  parts,  which  are 
connected  by  a  sleeve-coupling  with  right-  and  left-hand  threads. 
By  turning  the  coupling  the  valve-stem  is  lengthened  or  shortened, 
and  thus  the  position  of  the  valve  in  reference  to  the  centrifugal 
governor  is  changed.  The  coupling  may  either  be  turned  by  hand 
or  by  a  small  electric  motor  controlled  from  the  switchboard.2 

The  Voith  hydraulic  governor  is  also  provided  with  a  device 
by  which  the  speed  of  the  turbine  can  be  varied  while  the  turbine 
is  running.3  For  this  purpose  the  step  upon  which  the  spindle  of 
the  centrifugal  governor  revolves  may  be  raised  or  lowered  and 
thus  the  position  of  the  centrifugal  governor  changed  in  reference 
to  the  valve  controlling  the  relay.  The  raising  or  lowering  is 
done  by  a  screw  spindle,  which  may  either  be  turned  by  hand 
or  by  a  small  electric  motor  controlled  from  the  switchboard. 

In  Fig.  63  is  shown  a  simple  and  efficient  hydraulic  governor 
applied  to  an  impulse  turbine.  Its  action  is  as  follows:  In  the 
valve-chamber  g  is  the  admission-valve  r,  which  is  in  the  shape 
of  a  differential  plunger  and  is  kept  floating  by  the  difference  in 
water-pressure  existing  in  the  spaces  a  and  b.  The  pressure-water 
after  passing  through  the  filter  enters  the  valve-chamber  at  a  and 
flows  through  the  bore  in  the  admission-valve  into  the  space  6. 
The  pressure  in  space  b  is  regulated  by  the  size  of  the  vent-hole 
opening,  which  is  controlled  by  the  regulating-valve  v,  which  in 

1  Built  by  The  Lombard  Governor  Co.,   Boston,  Mass.     For  an  illustrated 
description  see  Frizell,  Water  Power,  p.  575. 

2  See  Engineering  News,  Jan.  15,  1903,  p.  62. 

3  Built  by  J.  M.  Voith,  Heidenheim,  Germany.     For  an  illustrated  descrip- 
tion see  Zeitsch.  d.  V.  deutsch.  Ing.,  June  20,  1903,  p.  894. 


154 


MODERN  TURBINE  PRACTICE. 


turn  is  moved  by  the  centrifugal  governor.  At  normal  speed  the 
admission-valve  r  is  in  the  middle  position  as  shown,  the  port  d 
of  the  relay  cylinder  being  closed.  Water  flows  continuously 
from  a  through  the  bore  in  tjie  admission-valve  r  to  the  space  b 


FIG.  63. — Hydraulic   Governor  for  Impulse  Turbines.      Built  by  Escher, 
Wyss  &  Co.,  Zurich,  Switzerland. 

and  from  there  through  the  vent-valve  to  the  space  c  and  then 
escapes  through  the  waste-pipe  shown. 

When  the  speed  of  the  turbine  decreases,  the  centrifugal  gov- 
ernor raises  the  regulating-valve  v,  the  pressure  in  the  space  b 
is  reduced,  and  the  admission-valve  raised,  permitting  the  pres- 
sure-water to  flow  from  a  through  the  port  d  into  the  relay-cylinder, 
forcing  down  the  relay-piston  and  thus  opening  the  tongue  of 


GOVERNORS  AND  SPEED  REGULATION.       155 

the  turbine-nozzle,  that  is,  increasing  the  gate-opening.  However, 
as  the  fulcrum  of  the  lever  which  moves  the  regulating-valve  v 
is  connected  to  the  piston-rod  of  the  relay-piston,  the  downward 
movement  of  this  piston  returns  or  lowers  the  regulating-valve  v, 
which  decreases  the  vent-hole  opening  and  thus  causes  an  increase 
in  the  pressure  in  the  space  6,  which  forces  the  admission-valve 
back  to  its  middle  position  and  thus  stops  the  motion  of  the  relay- 
piston  and  the  tongue.  With  an  increase  in  the  speed  of  the 
turbine,,  the  opposite  action  takes  place,  the  regulating-valve  v 
being  lowered  and  the  pressure  in  the  space  b  is  increased.  This 
forces  the  admission-valve  r  down  and  permits  the  pressure-water 
in  the  relay-cylinder  to  escape  through  port  d,  space  c,  and  the 
waste-pipe  shown;  and  the  water-pressure  existing  in  the  space 
above  the  tongue  and  below  the  relay-piston  forces  the  latter 
upwards. 

From  the  foregoing  description  it  will  be  noted  that  for  each 
position  of  the  relay-piston  and  the  tongue  or  gate,  there  is  a 
certain  corresponding  position  of  the  fly-balls  of  the  centrifugal 
governor  and  consequently  a  certain  corresponding  speed  of  the 
turbine. 

This  governor  is  very  sensitive  and  quick-acting  on  account 
of  the  small  mass  and  inertia  of  the  regulating-valve  v,  the  com- 
paratively large  areas  of  a,  6,  and  c,  the  floating  state  of  the  admis- 
sion-valve r,  and  the  continuous  flow  of  water  through  the  valve- 
chamber  g. 

In  Figs.  64  and  65  are  shown  two  forms  of  a  temporary  by- 
pass often  used  in  connection  with  and  controlled  by  a  governor. 

The  action  of  the  by-pass  shown  in  Fig.  64  is  very  similar 
to  that  of  the  admission- valve  of  the  governor  above  described. 
The  valve  is  in  the  shape  of  a  differential  plunger  and  has  a  hole 
bored  through  its  centre,  permitting  the  water  to  flow  to  the 
space  above  the  plunger.  The  pressure  in  the  space  above  the 
plunger,  which  holds  the  by-pass  closed,  is  controlled  by  a  conical 
valve,  which  receives  its  motion  from  the  piston-rod  of  the  relay- 
piston.  With  a  rise  in  the  speed  of  the  turbine  and  the  conse- 
quent reduction  in  the  gate-opening,  the  conical  valve  is  raised 
and  thus  the  pressure  above  the  plunger  relieved  and  the  plunger 
forced  upward  by  the  pressure  below  it;  that  is,  the  by-pass  is 


156 


MODERN  TURBINE  PRACTICE. 


opened,  the  extent  to  which  the  by-pass  is  opened  being  in  pro- 
portion to  the  extent  to  which  the  gate-opening  is  reduced.  The 
dash-pot  shown  above  the  conical  valve,  by  its  own  weight  gradu- 
ally lowers  the  conical  valve  again,  thus  permitting  the  pressure 
above  the  plunger  to  rise  and  to  close  the  by-pass.  The  by-pass 
is  of  such  a  size  that  when  necessary  the  entire  volume  of  water 


FIGS.  64  and  €5. — Two  Forms  of  Temporary  By-pass.     Built  by  Escher 
Wyss  &  Co.,  Zurich,  Switzerland. 

required  by  the  turbine  at  full  gate-opening  may  be  discharged 
through  it. 

The  wing-valve  of  the  by-pass  shown  in  Fig.  65  is  opened  by 
the  lever  H,  which  receives  its  motion  from  the  piston-rod  of 
the  relay-piston  and  the  weighted  dash-pot  gradually  closes  the 
by-pass  again. 

The  hydraulic  governor  described  above  is  used  for  regulating 
the  speed  of  the  double  impulse  turbine  shown  in  Figs.  54  to  56. 
The  by-pass  is  located  below  the  nozzles  and  the  dash-pot  on 


GOVERNORS  AND  SPEED  REGULATION.  157 

the  right  side  of  the  turbine,  as  shown  in  Fig.  54,  the  piston 
of  the  dash-pot  forming  the  counterweight  for  closing  the  by- 
pass. 

A  hydraulic  governor  having  a  combined  relay  and  by-pass 
and  using  oil  under  water-pressure  from  the  penstock  as  a  pressure- 
fluid  is  employed  in  the  regulation  of  the  impulse  turbine  shown 
in  Figs.  51  to  53.  The  centrifugal  governor,  relay,  and  return  act 
in  the  same  manner  as  above  described,  but  the  piston  of  the 
relay  serves  at  the  same  time  as  the  cylinder  for  a  second  piston 
L,  which  moves  inside  of  the  first  one  and  actuates  the  by-pass. 
The  by-pass  P  itself  is  similar  in  shape  to  the  turbine-nozzle  and 
is  opened  and  closed  by  a  slide  fastened  to  a  pair  of  bell-cranks, 
which  are  connected  to  the  by-pass  piston  and  whose  fulcrum 
is  in  line  with  the  axis  of  the  hinge  of  the  tongue.  The  slide  and 
its  seat  at  the  end  of  the  by-pass  nozzle  have  a  cylindrical  sur- 
face. With  the  turbine  running  at  normal  speed,  a  helical  spring 
surrounding  the  piston-rod  of  the  relay-piston  holds  the  by-pass 
slide  closed  and  resting  against  a  stop.  A  small  aperture  admits 
oil  to  the  space  between  the  relay  and  the  by-pass  pistons,  being 
sucked  into  this  space,  when  the  space  is  enlarged  by  the  relay- 
piston  moving  upwards  in  reference  to  the  by-pass  piston. 

With  an  increase  in v  the  speed  of  the  turbine  and  consequent 
downward  movement  of  the  relay-piston  and  the  tongue — that  is, 
a  reduction  in  gate-opening — the  oil  contained  in  the  space  between 
the  relay  and  by-pass  pistons  forces  the  by-pass  piston  also  down- 
ward, thus  opening  the  by-pass  slide,  but  the  pressure  of  the 
spring  gradually  moves  the  by-pass  piston  back  to  its  upper  posi- 
tion, thus  closing  the  by-pass  and  forcing  the  oil  contained  in 
the  space  between  the  relay  and  by-pass  pistons  out  through  the 
small  aperture,  the  speed  with  which  the  by-pass  closes  depending 
on  the  size  of  this  aperture. 

This  governor  keeps  the  speed  of  an  impulse  turbine  as  shown 
in  Figs.  51  to  53,  working  under  a  head  of  1312  ft.  and  supplied 
by  a  penstock  6560  ft.  long,  within  3%  of  the  normal  when  the 
full  load  of  several  hundred  horse-power  is  suddenly  thrown  off 
and  the  maximum  variation  in  pressure  in  the  penstock  is  only  10%. 

Figs.  66  to  68  show  a  hydraulic  governor  with  differential 
relay-piston.  This  governor  is  used  in  the  Elektrizitaetswerk 


158 


MODERN  TURBINE  PRACTICE. 


Beznau,  at  Beznau,  Switzerland,  a  cross-section  of  the  power-house 
of  this  plant  being  shown  in  Fig.  19. 


Fig.  69  shows  a  very  simple  hydraulic  governor  in  which  two 
plungers  are  employed  for  the  relay,  instead  of  a  piston. 


GOVERNORS  AND  SPEED  REGULATION. 


159 


The  hydraulic  governor  shown  in  Figs.  32  and  33,  in  connection 
with  the  turbine  for  the  regulation  of  which  it  is  used,  keeps  the 
speed  of  this  turbine  within  1J%  of  the  normal,  with  variations 
in  load  of  10%,  and  within  5%  of  normal  speed  when  the  full  load 
is  suddenly  thrown  off.  However,  a  small  fly-wheel  is  used  to  aid 
the  governor. 

.  Tests  made  with  the  hydraulic  governors  used  in  power-house 
No.  2  of   the  Niagara  Falls  Power  Company  gave  a  maximum 


FIG.   69. — Hydraulic  Governor.     (Built  by    Escher,  Wyss  &  Co.,   Zurich, 

Switzerland.) 

variation  from  the  normal  speed  of  the  turbines  of  3.8%  when 
the  full  load  of  5000  H.P.  was  thrown  off  as  rapidly  as  possible. 

In  many  large  steam-power  plants  one  steam-engine  takes 
care  of  the  regulation  of  the  whole  plant,  and  in  an  analogous 
manner  one  turbine  unit  and  governor  may  be  used  to  take  care 
of  the  regulation  of  a  large  water-power  plant. 

Builders  of  high-class  steam-engines  always  make  the  governor 


160  MODERN  TURBINE  PRACTICE. 

a  part  of  the  engine,  but  turbines  and  turbine-governors  are  at 
present  entirely  separate  machines,  and  the  governor  is  usually 
set  anywhere  about  the  plant ;  yet  it  would  be  well  for  the  turbine 
and  governor  builders  to  combine,  or  at  least  to  cooperate,  and 
to  mount  the  governor  on  the  main  frame  or  the  turbine-case, 
thus  making  the  whole  a  complete  and  self-contained  machine, 
as  is  now  the  general  practice  with  European  turbine-builders. 

In  contracting  for  a  governor,  it  should  be  clearly  stated  whether 
the  guaranteed  limit  in  speed  variation  of  the  turbine  to  be  regu- 
lated is  the  variation  either  way,  above  and  below  the  normal,  or 
the  total  variation  between  the  minimum  and  maximum  speed. 

The  guarantee  frequently  given  by  governor-builders,  that  their 
governor  will  give  a  regulation  as  good  or  better  than  any  other 
governor,  is  of  no  value,  as  the  purchaser  can  evidently  not 
test  all  other  makes  of  governors  to  prove  the  correctness  of  the 
guarantee. 


PAET  II. 

WATER-POWER  PLANTS 


CHAPTER  VIII. 
WATER-CONDUCTORS. 

Headrace  and  Tailrace. — Narrow  and  deep  headraces  and  tail- 
races  are  always  to  be  preferred  to  wide  and  shallow  ones,  as  the 
loss  in  head  is  less  in  a  deep  than  in  a  shallow  race,  but  the  greatest 
advantage  from  a  deep  race  is  derived  in  localities  where  thick  sur- 
face ice  is  formed  during  the  whiter  months,  as  such  ice  not  only 
greatly  reduces  the  passage  area  of  the  race,  but  also  offers  con- 
siderable frictional  resistance  to  the  flow  of  the  water. 

The  location  and  direction  of  the  entrance  to  a  headrace  should 
be  carefully  chosen  to  avoid,  as  far  as  possible,  the  tendency  of 
the  water  to  carry  sand  into  the  headrace.  Across  the  entrance 
of  a  headrace  should  be  placed  a  heavy  boom,  to  prevent  wood, 
ice,  and  floating  rubbish  from  entering  the  race.  A  crib  with 
water-passages  near  the  bottom  is  an  improvement  over  the  boom, 
and  should  be  arranged  for  the  use  of  stop-logs,  to  shut  out  the 
water  from  the  headrace  when  desired.1  A  boom  or  crib  should 
have  such  a  direction  that  floating  matter  will  not  lodge  against 
it  but  will  glance  off  and  be  carried  away  by  the  stream. 

All  bends  should  be  avoided  in  races,  but  where  necessary 
these  bends  should  be  of  long  radius. 

1  For  an  illustrated  description  of  such  a  crib  see  Engineering  News,  May  7, 
1903,  p.  400. 

161 


162  WATER-POWER  PLANTS. 

In  American  practice  the  speed  of  the  water  in  a  head-  or  tail- 
race  is  usually  2  to  3  ft.  per  second,  while  in  Europe  a  speed  of  1.5  ft. 
per  second  is  mostly  employed.  In  cold  climates  the  speed  of  the 
water  in  the  races  should  be  sufficiently  low,  that  is  not  over  3  ft. 
per  second,  so  as  to  allow  the  water  to  freeze  over  and  thus  prevent 
the  formation  of  anchor-ice  and  frazil  in  the  races. 

Water  carrying  much  sand  is  frequently  run  through  a  sand- 
settler,  if  the  volume  of  the  water  is  small.  Such  a  sand-settler 
is  a  basin  or  an  enlargement  in  the  headrace,  through  which  the 
water  flows  with  so  low  a  speed  as  to  permit  the  sand  to  be  pre- 
cipitated. Grooves  or  other  obstructions  are  placed  on  the  bottom 
and  at  right  angles  to  the  direction  of  the  flow  of  the  water,  to 
arrest  sand  rolling  along  the  bottom.  Sand-settlers  employed 
in  connection  with  open  timber  flumes  are  usually  large,  shallow 
wooden  boxes.  To  free  large  volumes  of  water  from  sand,  a  ditch 
is  often  placed  either  in  front  or  back  of  the  water-racks,  in  which 
at  least  the  sand  rolling  along  the  bottom  will  be  caught.  By 
means  of  an  18-  or  24-in.  pipe,  closed  by  a  gate  and  leading  to  some 
place  outside  of  the  heacjrace,  the  sand  accumulated  in  the  ditch 
may  occasionally  be  washed  or  scoured  out.  The  inlet  of  the  pipe 
should  be  protected  by  a  coarse  screen,  to  prevent  large  objects 
from  entering  and  lodging  in  the  pipe.  As  a  rule  it  will  be  found 
cheaper  to  let  the  sand  go  through  the  turbines,  and  to  renew  the 
guides  and  runners  when  worn  out,  than  to  attempt  to  free  large 
volumes  of  water  from  sand. 

Near  the  lower  or  power-house  end  of  the  headrace  should  be, 
placed  a  large  sluice-gate  and  wasteway,  to  discharge  ice  and 
floating  rubbish  from  the  headrace,  and  a  small  boom  may  be  used 
to  guide  such  floating  matter  to  the  gate. 

The  tailrace  under  the  turbines  should  be  arranged  to  give 
the  water  discharged  every  facility  for  escaping,  to  prevent  it 
from  backing  up  around  the  turbine  or  draft-tube.  The  walls 
of  the  tailrace  should  be  of  such  a  shape  as  to  deflect  the  water 
in  the  proper  direction,  but  where  draft-tubes  are  used  the  best 
arrangement  is  to  have  the  draft-tubes  curving  or  inclined  in  the 
direction  of  the  flow  of  the  water  in  the  tailrace.  Where  several 
draft-tubes  discharge  into  the  same  tailrace  it  is  advisable  to? 
place  these  draft-tubes  on  one  side,  as  they  will  thus  cause  less 


WATER-CONDUCTORS.  163 

obstruction  to  the  passage  of  the  water  than  when  placed  in  the 
centre  of  the  tailrace. 

In  localities  where  the  winter  is  severe  the  part  of  the  tail- 
race  located  under  the  power-house  should  be  protected  against 
extreme  cold,  to  prevent  an  excessive  accumulation  of  ice.  For 
this  purpose  the  upper  part  of  the  tailrace  opening,  that  is  the 
end  of  the  tailrace  where  it  emerges  from  under  the  power-house, 
should  be  boarded  up  to  within  1  or  2  ft.  of  the  normal  tailwater 
level,  and  to  the  bottom  of  this  wooden  partition  should  be  nailed 
a  strip  of  canvas  or  tarpaulin  of  such  a  width  that  its  lower  edge 
will  float  on  the  tailwater,  even  at  its  lowest  stage.  A  board 
hinged  to  the  bottom  of  the  wooden  partition  and  reaching  to 
the  level  of  the  tailwater  at  its  lowest  stage  may  be  used  instead. 

Water-racks.— Water-racks  will  give  reasonable  safety  against 
choking  or  damaging  the  turbines  if  the  space  between  the  bars 
is  less  than  the  least  clear  dimension  of  the  water-passages  in  the 
guide-  or  runner-buckets.  Temporary  choking  may  occur  with 
the  turbine-gates  nearly  closed,  but  this  can  usually  be  relieved 
at  once  by  opening  the  gates.  This  rule  may  be  employed  with 
the  European  type  and  small  sizes  of  the  American  type  of  tur- 
bine, but  the  larger  sizes  of  the  latter  give  too  great  a  spacing. 

Coarse  racks  are  sometimes  used  in  front  of  the  fine  racks, 
especially  where  the  fine  racks  are  not  protected  by  a  boom  or 
crib.  For  size  and  spacing  of  the  rack-bars,  the  following  figures 
are  considered  as  good  practice: 

Fine  racks:  Clear  space  between  bars  J  to  1J  ins.;  bars  of 
wrought  iron  or  steel,  J  to  f  in.  thick  by  3  to  4  ins.  wide. 

Coarse  racks:  Clear  space  between  bars  3  ins.;  bars  of  wrought 
iron  or  steel,  i  to  J  in.  or  even  1  in.  thick  by  4  to  5  ins.  wide. 

Water-racks  should  have  a  total  clear  area  for  the  passage  of 
water  much  in  excess  of  the  total  area  of  the  penstock  inlets, 
to  permit  the  passage  of  the  water  without  loss  of  head,  even 
with  the  rack  partly  clogged.  To  give  a  large  passage  area  and 
to  facilitate  cleaning,  the  racks  are  usually  inclined.  In  cal- 
culating the  strength  of  the  supporting  structure  for  a  water- 
rack,  it  is  customary  to  assume  some  arbitrary  pressure  against 
the  rack,  say  between  30  to  50  Ibs.  per  square  foot. 

Instead  of  a  continuous  rack,  firmly  fixed  in  position,  a  sectional 


164 


WATER-POWER  PLANTS. 


rack,  as  shown  in  Figs.  70  and  71,  should  be  used.  The  sections 
are  made  3  to  4  ft.  wide,  so  that  they  may  be  easily  handled,  and 
are  held  at  the  lower  end  by  a  pair  of  cast-iron  shoes,  and  at  the 


FIGS.  70  and  71. — Sectional  Water-rack. 

upper  end  by  clasps  or  latches  or  similar  means,  so  that  any  sec- 
tion can  be  taken  out,  repaired,  or  the  bars  straightened  and  put 
back  into  its  place,  without  the  employment  of  a  diver.  In  cold 
climates  such  racks  have  to  be  securely  held,  as  with  the  sur- 
face ice  frozen  to  the  bars  any  rise  in  the  water-level  would  lift 
the  racks  from  their  shoes. 


WATER-CONDUCTORS.  165 

Head-gates. — The  head-gate  is  used  for  shutting  off  the  water 
from  a  penstock,  open  turbine-chamber,  or  forebay,  and  in  America 
is  nearly  always  a  slide  moving  vertically.  Until  recently  head- 
gates  were  made  of  wood,  but  now  they  are  frequently  made  of 
steel  plate  and  structural  steel,  especially  if  of  large  size.  Sliding 
gates  are  moved  either  by  means  of  racks  and  pinions  or  screw- 
spindles,  operated  by  hand,  or  mechanical  or  electric  power,  or 
by  means  of  hydraulic  lifts.  Gates  that  are  likely  to  get  out  of 
line  while  being  moved,  and  thus  to  bind  or  jam  hi  their  slides, 
should  be  provided  with  a  squaring-shaft.1  Such  a  squaring-shaft 
is  particularly  required  where  two  hydraulic  lifts  are  used  for  one 
gate,  as  otherwise  the  piston  of  one  lift  might  move  faster  than 
the  other  one. 

For  large  sliding  head-gates  a  by-pass  or  balance-port  is  usu- 
ally employed,  by  which  the  water-pressure  hi  front  and  back 
of  the  gate  can  be  balanced  before  moving  the  gate. 

In  Figs.  72  to  75  is  shown  a  sliding  steel  head-gate  provided 
with  a  balance-port.  The  gate  is  made  hi  two  sections,  the  upper 
section  being  much  smaller  than  the  lower  one.  The  horizontal 
joint-faces,  where  the  sections  meet,  are  planed.  The  gate-stem 
is  fastened  to  the  upper  section  only,  and  the  two  sections  are 
connected  by  two  rods,  which,  however,  leave  the  upper  section 
free  to  move  12  ins.  without  moving  the  lower  section,  so  that 
when  the  upper  section  is  raised  the  two  sections  will  separate, 
leaving  an  opening  or  port  12  ins.  in  height  by  the  full  width  of  the 
gate,  thus  permitting  the  water  to  fill  the  penstock  and  create  a 
back-pressure.  When  the  gate  is  balanced  by  this  back-pressure 
the  raising  of  the  upper  section  is  continued,  and  engaging  the  nuts 
on  the  rods  connecting  the  two  sections,  the  lower  section  is  raised 
with  it. 

If  it  is  required  to  keep  the  balance-port  open  while  the  gate 
is  being  lowered,  two  latch-rods  are  provided,  running  up  to 
the  gate-operating  platform.  By  giving  the  latch-rods  a  quarter- 
turn  the  latches  are  thrown  hi  and  keep  the  sections  separated. 
When  the  lower  section  is  fully  closed  the  latches  are  thrown  out 
and  the  upper  section  is  closed. 

1  See  Frizell,  "Water-power,"  p.  239. 


166 


WATER-POWER  PLANTS. 


•''^v'-'-^^y^ 

—----.--.:»"--  y -7j'r--*< 

FIGS.  72  to  75.— Steel  Head-gate  with  Balance-port. 


WATER-CONDUCTORS.  167 

In  Figs.  76  and  77  is  shown  a  sliding  steel  head-gate  provided 
with  rollers  to  reduce  the  friction  between  the  gate  and  the  slides. 
The  gate  is  kept  tight  at  the  sides  by  a  curved  plate,  which  is 
pressed  against  the  plate  fastened  to  the  masonry,  by  the  water- 
pressure. 

Figs.  78  and  79  represent  a  pivoted  steel  head-gate,  which  is  also 
shown  in  position  in  the  power-house  cross-section  Fig.  21.  The 
pivot  is  so  located  that  the  gate  is  nearly  balanced. 

In  cold  climates  all  head-gates  which  raise  above  the  water  level 
should  be  so  arranged  that  they  are  entirely  below  the  surface  ice 
when  closed  and  entirely  above  the  surface  ice  when  open,  to 
prevent  them  from  freezing  fast.  In  a  well-known  water-power 
plant  in  New  York  State,  using  very  large  sliding  steel  head-gates, 
it  is  often  necessary  in  freezing  weather,  after  the  plant  has  been 
shut  down  over  Sunday,  to  use  dynamite  and  jack-screws  on  the 
penstock  side  of  the  gates,  which  is  accessible,  to  get  the  gates 
started  before  they  can  be  raised. 

Gates  sliding  horizontally,  and  thus  remaining  always  below 
the  water  level  or  surface  ice,  may  be  used  in  some  cases. 

An  interesting  head-gate,  and  deserving  a  more  general  applica- 
tion, is  shown  in  the  power-house  cross-section  Fig.  20.  This  is 
a  cylinder  gate  made  of  cast  iron  and  double-seated,  the  lower 
seat  being  formed  by  a  ring  fastened  to  the  bottom  of  the  headrace 
or  forebay,  and  the  upper  seat  by  the  raised  edge  of  the  dome  or 
head,  the  dome  being  supported  by  vertical  steel  bars  fastened  to 
the  lower  seat  or  ring.  The  gate  itself  is  a  cylinder  cast  in  halves 
and  bolted  together.  This  cylinder  is  connected  to  the  ends 
of  two  yokes  by  four  short  links,  and  each  yoke  is  attached  to  a 
chain,  by  which  the  gate-cylinder  may  be  raised  or  lowered.  In 
the  center  of  the  dome  is  a  small  filling-gate,  moved  by  a  separate 
chain. 

The  cylinder  head-gate  has  the  advantage  that  it  is  practically 
balanced  and  thus  requires  little  power  to  operate,  it  requires  only 
a  movement  equal  to  one  quarter  of  the  diameter  of  the  inlet  to 
open  or  close,  it  lemains  always  below  the  water  level  or  surface 
ice,  and  it  can  be  made  perfectly  tight.  Sand  and  stones  rolled 
along  the  bottom  of  the  headrace  by  the  water  can  be  prevented 
from  entering  the  penstock  by  raising  the  lower  seat  or  ring  above 


168 


WATER-POWER  PLANTS. 
J- — •' *" 


•SZ50- 


FIGS.  76  and  77.— Steel  Head-gate  with  -Friction-rollers. 


3SOO 


FIGS.  78  and  79.— Pivoted  Steel  Head-gate. 


WATER-CONDUCTORS.  169 

the  bottom.  In  localities  where  there  is  no  ice  formation  a 
cylinder  head-gate  may  be  used,  which  is  seated  only  at  the  lower 
end,  while  the  upper  end  projects  above  the  water  level  and  is 
guided  by  rollers. 

Stop-log  slides  should  be  provided  in  front  of  all  head-gates, 
so  that  the  water  can  be  shut  out  and  the  gates  and  slides  or  seats 
made  accessible  for  inspection  and  repairs. 

Penstocks. — Penstocks  or  feeder-pipes  should  always  be  as  short 
as  possible,  even  when  a  shorter  penstock  involves  a  greater 
expenditure  for  excavation,  etc.  This  is  for  the  reason  that  the 
shorter  the  penstock  the  better  it  is  for  the  speed  regulation  of  the 
turbines,  and  the  less  steel-plate  work  has  to  be  kept  painted  and 
repaired. 

The  following  rules  should  be  observed  when  determining  the 
cross-sectional  area  of  the  conductors  which  convey  the  water  to- 
and  from  the  turbines: 

The  speed  of  the  water  should  be  gradually  increased  from 
the  speed  in  the  headrace,  usually  2  or  3  ft.  per  second,  to  the 
penstock  speed,  by  means  of  a  cone  or  taper  piece.  Near  the 
lower  end  of  the  penstock  the  speed  should  again  be  gradually 
increased,  so  that  the  water  will  arrive  at  the  guide-buckets  with 
a  speed  equal  to  that  with  which  it  has  to  enter  these  guide-buckets. 
At  the  entrance  of  the  draft-tube,  or  draft-tube  elbow  or  tee,  the 
water  should  have  a  speed  equal  to  the  absolute  velocity  with 
which  it  leaves  the  runner-buckets,  and  should  then  gradually 
decrease  to  a  speed  of  about  2  or  3  ft.  at  the  lower  end  of  the  draft- 
tube.  A  speed  of  2  or  3  ft.  is  also  usually  chosen  for  the  tailrace. 

In  general  it  should  be  stated:  Avoid  changes  of  speed  of  the; 
water  where  possible,  but  where  such  changes  are  necessary  make 
them  gradually;  also,  avoid  changes  of  direction  of  water,  but 
where  such  changes  are  necessary  use  curves  of  long  radius. 

The  arrangement  often  employed  of  having  at  the  lower  end 
of  the  penstock  and  at  right  angles  to  the  same  a  drum  or  receiver 
of  much  larger  diameter  than  the  penstock  itself,  from  which 
drum  a  number  of  turbines  are  supplied  by  branches  set  at  right 
angles  to  the  drum,  must  be  condemned  on  account  of  the  abrupt 
changes  in  speed  and  direction  of  the  water. 

All  nozzles  or  branches  of  penstocks  should  be  at  an  angle  of 


170  WATER-POWER  PLANTS 

not  over  45°  to  the  penstock,  or,  in  other  words,  the  directions 
of  flow  of  the  water  in  the  penstock  and  in  the  nozzle  or  branch 
should  form  an  angle  of  not  over  45°  with  each  other.  Directly 
beyond  each  nozzle  or  branch  the  diameter  of  the  penstock  should 
be  reduced,  to  keep  the  speed  of  the  water  uniform. 

When  determining  the  speed  for  the  water  in  the  penstock  all 
conditions  should  be  carefully  considered,  and  it  should  also  be 
borne  in  mind  that  the  friction  loss  in  a  penstock  varies  with  the 
square  of  the  speed. 

Conditions  making  a  low  speed  advisable  are:  Low  head, 
large  diameter  of  penstock,  great  length  of  penstock,  many  bends 
in  penstock,  variable  loads  on  the  turbines,  regulation  of  speed  of 
turbines  by  changing  the  amount  of  water  used. 

Conditions  making  a  high  speed  permissible  are:  High  heads, 
small  diameter  of  penstock,  short  penstock,  few  or  no  bends  in 
penstock,  steady  loads  on  the  turbines,  regulation  of  speed  of 
turbines  by  by-pass. 

Many  hydraulic  engineers  employ  in  all  cases  a  penstock 
speed  of  3  ft.  per  second,  but  it  is  often  of  advantage  to  greatly 
exceed  this  velocity.  From  a  great  number  of  well-designed 
water-power  plants  constructed  in  America  and  Europe  during 
recent  years  the  writer  has  deduced  the  following  table  of  highest 
permissible  speeds  of  water  in  penstocks  of  a  length  of  1000  ft.  or 
less,  with  easy  bends,  and  provided  with  proper  arrangements  for 
the  protection  of  the  penstocks  against  water-hammer: 

Diameter    of    penstock,    in 

feet 4        5        6        7        8        9       10     11      12 

Speed  of    water,  feet    per 

second 12     11.5     11     10.5     10     9.5      9      8.5      8 

In  penstocks  of  1  or  2  ft.  diameter  speeds  as  high  as  20  to  30  ft. 
have  been  used.  With  very  low  heads  the  penstock  speed  is  often 
limited  by  the  amount  of  head  that  it  is  permissible  to  lose  in  the 
penstock. 

The  principal  losses  in  the  head  of  the  water  while  entering  the 
penstock  and  flowing  through  the  penstock  and  draft-tube  are 
due  to  the  following  causes: 

(1)  The  entrance  loss.    This  loss  may  be  kept  low  by  having 


W  VTER-CONDUCTORS.  171 

a  large  entrance  connected  to  the  penstock  by  an  easy  cone  or 
taper  piece.  With  the  usual  head-gate  arrangement  such  large 
entrance  openings  require  very  heavy  and  cumbersome  gates 
for  penstocks  of  large  diameter,  but  there  is  no  reason  why  this 
taper  piece  could  not  be  partly  or  wholly  in  front  of  the  gate  and 
inside  the  headrace  or  forebay.  The  penstock  entrance  should 
-always  be  as  much  below  the  surface  of  the  water  as  circumstances 
will  permit. 

(2)  The  friction  loss:   This  loss  may  be  kept  down  by  a  low 
speed  of  water,  and  by  smooth  interior  of  the  penstock  and  draft- 
tube. 

(3)  The  loss  due  to  changes  in  direction  of  flow.     This  loss 
may  be  kept  down  by  using  as  few  and  as  easy  bends  as  possible. 

(4)  The  loss  caused  by  changes  in  speed  of  the  water.     This 
loss  is  due  to  the  conversion  of  part  of  the  energy  in  the  water 
into  another  form,  and  may  be  kept  low  by  having  as  few  and  as 
gradual  changes  as  possible. 

(5)  The  loss  due  to  the  speed  of  the  water  while  leaving  the 
lower  end  of  the  draft-tube.     This  loss  is  equal  to  the  velocity 
liead,   corresponding  to  the  speed  with  which  the  water  leaves 
the  draft-tube,  and  may  be  kept  down  by  making  this  speed  low. 

Many  engineers  regard  the  velocity  head  corresponding  to  the 
speed  of  the  water  in  the  penstock  as  a  total  loss,  but  this  is, 
of  course,  not  the  case. 

Penstocks  are  usually  made  of  tank-steel,  but  for  penstocks 
carrying  water  at  high  speeds  shell-plate  steel  should  be  used, 
having  an  ultimate  strength  of  55,000  to  65,000  Ibs.  per  square 
inch  and  an  elongation  of  22%  in  8  ins. 

A  factor  of  safety  of  3  to  4  may  be  used  for  short  penstocks 
of  large  diameter,  carrying  water  at  low  speeds  and  supplying 
turbines  with  steady  loads  or  regulated  by  means  of  a  by-pass. 
A  factor  of  safety  of  4  to  6  may  be  adopted  for  long  penstocks 
of  small  diameter,  carrying  water  at  high  speeds  and  supplying 
turbines  with  variable  loads  regulated  by  changing  the  amount 
of  water  used. 

The  factors  of  safety  here  given  are  fully  sufficient  in  all  cases, 
as  steel-plate  penstocks  very  rarely  fail  by  bursting  but  are 
destroyed  by  pitting,  that  is  the  formation  of  rust-holes,  Usually 


172  WATER-POWER  PLANTS. 

a  higher  factor  of  safety  is  employed  for  the  lower  end  than  /or 
the  rest  of  the  penstock,  as  the  effect  of  water-hammer  is  the 
greatest  at  the  lower  end.  Large  penstocks,  carrying  water  under 
a  very  low  head,  have  often  to  be  made  of  thicker  plate  than  the 
water-pressure  would  require,  to  prevent  them  from  flattening  or 
collapsing  by  their  own  weight  when  empty. 

Long  penstocks,  carrying  water  at  high  speed,  should  be  pro- 
vided with  a  safety-head,  besides  the  usual  devices  for  the  pro- 
tection of  the  penstock  against  water-hammer.  For  this  pur- 
pose a  cast-iron  or  angle-bar  flange  is  riveted  to  the  lower  end 
of  the  penstock,  to  which  flange  the  head,  closing  the  lower  end, 
is  bolted.  The  flange-bolts  should  have  a  factor  of  safety  of  not 
more  than  about  half  the  factor  employed  for  the  rest  of  the  pen- 
stock. Between  flange  and  head  a  packing  of  dry  white  pine 
should  be  used  which,  when  water  is  admitted  to  the  penstock, 
swells  and  makes  a  tight  joint.  Where  the  end  cannot  be  used 
for  this  purpose,  large  nozzles  may  be  riveted  to  the  penstock,, 
located  as  nearly  as  possible  in  the  line  of  the  water-hammer^ 
and  closed  by  heads  secured  as  just  described.  The  end  of  the 
penstock  or  the  nozzles  should  be  so  situated  that,  should  the 
heads  blow  out,  no  damage  will  be  done  by  the  jet  of  water  issuing 
from  the  opening.  This  arrangement  will  not  only  save  the  pen- 
stock and  turbines  from  being  wrecked  in  case  of  severe  water- 
hammer,  but  also  the  power-house  from  being  demolished  by  the 
water  set  free. 

Ample  air-inlets  should  be  provided  at  the  upper  end  of  the 
penstock,  as  shown  in  Fig.  75r  as  otherwise — should  the  safety- 
head  by  some  chance  give  way,  or  the  turbine-gates  or  turbine 
stop-valves,  if  such  are  employed,  be  opened,  while  the  head- 
gate  is  closed  but  the  penstock  full  of  water — the  penstock  might 
collapse  by  the  vacuum  created  in  its  interior.  Care  must  be 
taken  to  prevent  the  water  in  the  vents  or  air-inlets  from  freezing; 
as  this  would  render  them  useless. 

A  penstock  which  is  carried  for  a  considerable  distance  at 
about  the  same  elevation  as  that  of  its  inlet  and  with  so  little 
slope  as  to  be  nearly  horizontal,  and  then  descends  to  the  power- 
house on  a  steep  grade,  is  liable  to  collapse  when  the  turbine- 
gates  are  opened  quickly,  as  the  water  in  the  inclined  part  has 


WATER-CONDUCTORS.  1 73 

the  tendency  to  increase  its  speed  more  quickly  than  tne  water 
in  the  horizontal  part,  and  may  thus  break  away  from  the  latter 
and  cause  a  vacuum  in  the  penstock.  An  air-inlet  valve  will 
prevent  this,  but  it  is  better  to  have  a  small  compensating  or 
equalizing  reservoir  at  the  junction  of  the  horizontal  and  inclined 
part  of  the  .penstock.  Such  a  reservoir  may  be  built  of  steel 
plate,  concrete,  or  masonry,  and  will  not  only  prevent  the  collapse 
of  the  penstock  from  the  cause  above  named,  but  will  also  greatly 
improve'  the  regulation  of  the  turbines  and  decrease  the  water- 
hammer  in  the  penstock,  acting,  in  fact,  in  the  same  manner  as 
a  stand-pipe. 

Expansion- joints  in  penstocks  are  not  so  important  as  is  often 
asserted,  as  most  penstocks  contain  bends  which  permit  of  a 
limited  movement,  large  enough  to  compensate  for  expansion 
and  contraction,  but  in  a  straight  penstock,  rigidly  held  at  each 
end,  the  strains  due  to  changes  in  temperature  are  very  heavy. 
The  amount  of  these  strains  depends  on  the  modulus  of  elasticity 
and  the  coefficient  of  expansion  of  the  material;  being  for  medium 
steel  equal  to  200  Ibs.  per  square  inch  for  a  change  in  tempera- 
ture of  1°  F.  For  example,  a  straight  steel  penstock  9  ft.  in  diam- 
eter and  made  of  f-in.  plate  has  a  cross-section  of  metal,  including 
the  laps,  of  about  220  sq.  ins.,  and  if  held  rigidly  at  both  ends 
will  exert  a  thrust  or  pull  of  44,000  Ibs.  or  22  tons  for.  each  degree 
of  rise  or  fall  in  temperature;  and  assuming  a  rise  and  fall  of  50° 
from  a  mean  temperature  of,  say,  40°,  or  a  total  range  of  from 
— 10°  to  +  90°,  and  further  assuming  that  the  penstock  was  erected 
at  the  mean  temperature  of  40°,  the  greatest  thrust  or  pull  will 
be  10,000  Ibs.  per  square  in.,  or  1100  tons  for  the  whole  penstock. 
These  figures  show  that  an  expansion- joint  should  be  provided 
in  a  straight  penstock. 

The  lower  end  of  a  penstock  should  be  held  very  securely 
in  all  cases  to  prevent  forces  due  to  temperature  changes  and 
other  causes  from  throwing  the  turbines  out  of  alinement,  crack- 
ing the  power-house  walls,  etc. 

Steel-plate  penstocks  are  usually  made  in  small  and  large 
courses  and  lap-riveted.  Butt-strap  joints,  with  a  single  butt- 
strap  on  the  outside,  offer  less  frictional  resistance  to  the  flow 
of  the  water,  but  are  more  expensive.  A  manhole  should  be 


174  WATER-POWER  PLANTS. 

provided  at  the  upper  end  of  a  penstock,  as  shown  in  Fig.  75, 
and  at  the  lower  end  also,  if  required.  When  repainting  the 
inside  of  a  penstock  or  repairing  the  same,  the  water  leaking 
through  the  head-gate  should  be  prevented  from  running  down 
the  penstock,  and  for  this  purpose  a  small  outlet-nozzle,  about 
'6  in.  in  diameter  and  closed  by  a  blank  flange,  is  provided  at  the 
lower  side  of  the  upper  end  of  the  penstock,  as  shown  in  Fig.  75, 
and  by  building  a  small  dam  of  clay  in  the  penstock,  just  beyond 
this  nozzle,  the  leakage  is  prevented  from  flowing  down  the  pen- 
stock. All  openings  in  penstocks  for  large  nozzles,  branches, 
manholes,  etc.,  should  be  reinforced  by  steel-plate  rings,  riveted 
around  the  openings,  to  make  up  for  the  material  cut  away  by 
the  opening. 

If  a  stop-valve  is  to  be  used  at  the  lower  end  of  a  penstock 
or  its  branch,  a  union  similar  to  the  one  seen  in  the  draft-tube  of 
the  turbine  shown  in  Fig.  34,  but  with  flanged  and  bolted  joints, 
should  be  employed  to  facilitate  getting  the  valve  out  for  repairs 
and  returning  it  into  position,  without  moving  the  penstock  or 
turbine-case. 

As  the  exact  length  of  a  long  penstock  cannot  be  obtained 
beforehand,  requiring  perhaps  surveys  over  rocky  mountain-sides 
or  through  dense  forests,  a  large  course,  called  a  shearing-strip, 
should  be  left  out  at  about  the  middle  of  each  long  tangent  or 
straight  part.  The  provisional  length  of  this  shearing-strip  should 
be  about  one  half  the  length  of  a  regular  course,  thus  leaving  one 
half  the  length  of  a  course  either  way,  to  make  up  any  inaccuracies 
in  the  first  measurements  for  the  penstocks.  The  curves  of  a 
penstock  are  usually  built  first  and  then  the  straight  parts  con- 
structed, the  shearing-strip  being  supplied  from  actual  measure- 
ment, after  all  the  rest  of  the  penstock  has  been  riveted  up. 

Penstocks  should  be  calked  both  inside  and  outside,  and  the 
plates  thoroughly  cleaned  by  scrapers  and  wire  brushes  before 
painting.  Of  paints  used  for  the  protection  of  penstocks  may  be 
named  the  iron  and  lead  oxide  paints,  the  graphite  paints,  coal- 
tar,  asphaltum,  and  the  various  patented  compounds,  but  none 
can  be  said  to  satisfy  all  requirements. 

The  riveting,  calking,  and  painting  inside  of  a  small  penstock, 
where  the  workman  has  to  lie  down,  or  in  a  large  penstock,  where 


WATER-CONDUCTORS.  175 

scaffolds  have  to  be  used,  and  such  penstocks  running  down  a 
steep  mountain-side,  is  a  very  arduous  task  and  the  workmanship 
should  therefore  be  carefully  inspected,  as  the  men  are  liable 
to  slight  such  work.  In  hot  weather  a  penstock  exposed  to  the 
sun's  rays  will  become  intolerably  hot,  and  men  having  to  work 
inside  of  such  a  penstock  should  have  their  working  hours  from 
about  10  P.  M.,  when  the  penstock  has  had  time  to  cool  off,  to  about 
9  A.M. 

Masonry  piers  are  often  damaged  by  the  expansion  and  con- 
traction of  the  penstock  they  support,  and  the  paint  is  rubbed  off 
the  penstock  where  it  rests  on  the  piers.  Such  unprotected  places 
are  hidden  from  view  by  the  masonry,  and  are  apt  to  corrode  very 
quickly,  as  water  is  always  retained  between  the  surfaces  of  contact 
of  the  masonry  and  the  penstock.  It  is  therefore  preferable  to 
use  steel  piers  on  concrete  or  masonry  bases,  as  shown  in  Fig.  80. 

Such  steel  piers  are  cheaper  than  concrete  or  masonry  piers; 
they  leave  every  part  of  the  penstock  accessible  for  painting  and 
repairs,  and  are  free  to  swing  on  their  bases,  like  inverted  pendu- 
lums, to  accommodate  themselves  to  any  movements  of  the  pen- 
stock caused  by  changes  in  temperature.  The  uprights  or  posts  of 
these  piers  are  provided  with  bolt-holes,  to  fasten  to  them  the 
studs  for  a  housing  over  and  around  the  penstock  when  desired. 

Except  where  the  distance  between  the  penstock  and  the 
ground  varies  considerably,  the  steel  piers  are  all  made  the  same, 
and  the  variations  in  the  height  of  the  penstock  above  the  rock 
or  solid  ground  are  made  up  in  the  height  of  the  concrete  or 
masonry  bases.  The  uprights  of  the  steel  piers  are  anchored  to 
the  bases,  or,  if  the  latter  are  of  small  height,  through  the  bases 
to  the  rock  below. 

A  penstock  running  down  a  steep  mountain-side  must  be  pre- 
vented from  sliding  down  the  slope.  Where  concrete  or  masonry 
piers  are  employed,  it  is  often  sufficient  to  rivet  short  pieces  of 
heavy  angle-bars  to  the  penstock  and  having  these  bars  bear 
against  the  up-hill  side  of  the  piers,  but  with  steel  piers  the  pen- 
stock must  be  anchored  to  the  rock  or  special  anchor-piers.  It  is 
well  to  have,  in  any  case,  a  specially  heavy  concrete  or  masonry  pier 
at  the  lower  end  of  the  penstock,  to  prevent  the  latter  from 
throwing  the  turbines  out  of  alinement. 


176 


WATER-POWER  PLANTS. 


In  a  climate  like  that  of  the  northern  part  of  the  United  States 
and  of  Canada  penstocks  must  be  covered  or  boxed  in  to  protect 
them  from  the  extreme  cold,  otherwise  ice  will  form  on  their  inner 


1 


I 


surfaces.  At  Grand'Mere,  Que.,  a  penstock  of  14  ft.  diameter, 
left  unprotected  during  the  first  winter,  was  found  to  have  its 
interior  surface  covered  with  solid  crystal  ice  of  from  12  to  18  ins. 
in  thickness. 

During  midsummer  the  heat  of  the  sun's  rays,  acting  on  an 


WATER-CONDUCTORS.  177 

empty  penstock,  will  often  injure  the  paint,  cause  it  to  blister 
off,  and  perhaps  overstrain  the  penstock  itself,  and  a  covering 
will,  therefore,  prove  an  advantage  both  in  cold  and  hot  weather. 
Even  in  a  well-protected  penstock  ice  will  be  formed  in  severe 
weather  when  the  water  in  it  is  allowed  to  remain  stationary  for 
more  than  a  few  hours  at  a  time. 

Where  the  ground  under  a  penstock  consists  of  earth  it  is 
preferable  to  bury  the  penstock  below  the  frost-line,  like  the  water- 
mains  in  a  city  street. 

A  buried  penstock  is  free  from  the  bending  strains  occasioned 
in  a  penstock  supported  on  piers  by  the  unsupported  length 
between  the  piers,  but  a  buried  penstock  of  large  diameter  will 
require  stiffening  angles  to  be  riveted  to  the  upper  half  of  its  cir- 
cumference, to  prevent  it  from  collapsing  by  the  weight  of  the 
earth  above  it. 

The  cost  of  burying  a  penstock  will  be  about  the  same  -as  when 
masonry  piers  are  used,  as  the  following  figures  will  show:  A  pen- 
stock 4  ft.  in  diameter,  supported  by  masonry  piers  spaced  15  ft. 
center  to  center,  requires  piers  of,  say,  8X6X2  ft.  hi  mean  dimen- 
sions, containing  about  3J  cu.  yds.  of  masonry  each,  and  costing,  in- 
cluding the  necessary  excavation  for  the  base,  at  least  $25  to  $35 
a  pier.  A  ditch  6  ft.  wide  and  9  ft.  deep,  in  a  length  of  15  ft.,  con- 
tains 30  cu.  yds.,  and,  at  50  cts.  per  cubic  yard  for  excavation 
and  30  cts.  for  filling  and  tamping,  costs  $24,  to  which  may  be 
added  $6  for  drain,  lumber  required,  etc.,  making  a  price  of  $30  per 
length  of  15  ft.  Further,  while  the  penstock  buried  in  the  ground 
has  the  best  possible  protection  against  extremes  in  temperature, 
an  additional  expense  will  be  required  to  protect  the  penstock 
supported  on  piers. 

Under  the  penstock,  in  the  center  of  the  ditch,  should  be  a 
drainage-ditch  about  1  ft.  square  in  cross-section,  and  filled  with 
pebbles  or  broken  stone,  as  used  for  concrete-making.  The  pen- 
stock should  rest  on  short  wooden  blocks,  and  the  main  ditch 
should  be  left  open  during  the  first  year,  or  for  one  winter  season 
at  least,  after  which  the  penstock  is  carefully  inspected,  recalked 
where  leaky,  and  repainted  inside  and  outside,  after  which  the  earth 
is  packed  under  and  around  the  penstock  and  the  ditch  filled  in, 
removing  the  wooden  blocks  as  the  work  proceeds. 


178  WATER-POWER  PLANTS. 

Wooden  penstocks  or  stave-pipes  deserve  a  wider  application 
than  they  have  so  far  found  in  the  Eastern  States.  Wooden 
penstocks  are  cheaper  and  will  last  longer  than  steel  penstocks, 
need  less  protection  against  extremes  in  temperature,  and  require 
no  painting.  Their  interior  surfaces  are  smoother  than  those  of 
steel  penstocks  and  therefore  offer  less  frictional  resistance  to  the 
flow  of  the  water.1 

Wooden  penstocks  are  made  of  staves  from  2  to  4  ins.  thick 
and  from  6  to  8  ins.  wide,  planed  to  the  proper  shape  and  held 
together  by  round  iron  or  steel  rods,  connected  by  hoop-locks. 
The  staves  must  be  thick  enough  or  the  hoops  spaced  closely 
enough  to  prevent  the  staves  from  bulging  out  between  the  hoops. 
Thick  staves  are  usually  provided  on  one  edge  with  a  bead  of 
from  ^  to  J  in.  in  height  by  J  to  f  in.  in  width  and  located  next 
to  the  inner  side  of  the  stave,  as  with  such  a  bead  it  will  require 
less  strain  in  the  hoops  to  make  the  penstock  water-tight. 

The  joints  at  the  ends  of  the  staves  are  usually  made  by  steel 
tongues,  driven  into  kerfs.  These  joints  must  be  well  broken. 

Curves  in  wooden  penstocks  require  a  long  radius  and  there- 
fore their  horizontal  and  vertical  alinement  must  be  located  on 
the  ground,  like  a  railroad  line.  The  minimum  radius,  in  feet, 
that  can  be  used  in  a  wooden  penstock  is  about  R=12.5xDpXts, 
in  which  Dp  is  the  inside  diameter  of  the  penstock  in  feet  and 
tg  the  thickness  of  the  staves  in  inches.  Where  a  smaller  radius 
is  required,  a  section  of  steel  penstock  has  to  be  inserted  in  the 
wooden  one  for  the  purpose. 

The  wood  employed  should  be  clear  and  sound  and  free  from 
pitch,  so  that  the  staves  will  become  saturated  by  the  water. 
The  wood  used  for  such  stave-pipes  is,  in  the  order  of  its  value 
for  the  purpose:  California  redwood,  Douglas  spruce  (also  called 
Douglas  fir),  spruce,  white  pine,  southern  pine,  and  cypress. 

The  staves  of  a  wooden  penstock  that  is  not  left  empty  long 
enough  to  allow  the  wood  to  dry  will  last  much  longer  than  the 
hoops,  and  the  hoops  may  be  renewed,  when  destroyed  or  weakened 

1  For  a  very  complete  paper  on  wooden  penstocks  see  Mr.  Arthur  L.  Adams, 
"Wood-stave  Pipe:  its  Economic  Design  and  Use/'  read  before  the  meeting 
of  the  Am.  Soc.  C.  E.,  Oct.  19,  1898;  also  an  abstract  in  Engineering  News, 
Oct.  27,  1898,  p.  259. 


WATER-CONDUCTORS. 

by  rust,  by  placing  new  ones  between  the  old  hoops,  if  the  sound- 
ness of  the  staves  will  warrant  it.  A  stop-valve  should  be  used 
at  the  lower  end  of  a  wooden  penstock  and  no  head-gate  at  the 
upper  end,  to  insure  the  penstock  being  always  full  of  water, 
which  may  be  shut  out  by  the  use  of  stop-logs  in  case  of  necessity. 
A  wooden  penstock  buried  in  the  ground  may  be  left  empty  for 
some  time,  without  danger  of  the  staves  drying  out. 

For  heads  cf  200ft.  and  more  in  height  wooden  penstocks  are 
not  economical,  as  the  hoops  require  as  much  metal  as  the  plates 
for  a  steel  penstock. 

Penstocks  constructed  of  concrete  and  steel  also  deserve  a 
wide  application  and  should  outlast  both  the  steel  and  wooden 
penstock,  as  the  steel  rods  are  protected  by  the  concrete.1 

Instead  of  welding  together  the  ends  of  the  embedded  hoops, 
these  ends  may  be  run  past  each  other  for  a  distance  of  from  30  to 
40  times  the  diameter  of  the  hoop-rod,  or  an  inch  or  so  of  each 
end  of  the  hoop-rod  may  be  bent  back  flat  on  itself,  and  the  ends 
run  past  each  other  for  a  distance  of  from  20  to  30  times  the  diam- 
eter of  the  hoop-rod.  For  small  concrete  penstocks  steel  wire 
wound  spirally  can  be  used  to  form  the  hoops. 

For  heads  of  200  ft.  and  more  in  height  penstocks  built  of 
concrete  and  steel  are  not  economical,  as  the  hoops  require  as- 
much  metal  as  the  plates  for  a  steel  penstock. 

Stand-pipes  may  be  built  either  of  steel  plate  or  of  concrete 
and  steel.  An  excellent  arrangement  is  to  have  a  concrete  base 
straddling  the  penstock,  and  the  stand-pipe  placed  on  top  of  this, 
base,  like  a  steel  chimney  or  stack.2 

1  An  illustrated  description  of  a  ferro-concrete  penstock  will  be  found  in 
Engineering  News,  Jan.  22,  1903,  p.  74. 

2  For  an  illustration  of  such  a  stand-pipe  see  Engineering  Magazine,  Feb. 
1903,  p.  686. 


CHAPTER  IX. 
THE  DEVELOPMENT. 

Developing  a  Water-power.1 — The  hydraulic  engineer,  before 
undertaking  the  development  of  a  water-power,  should  make  a 
thorough  study  of  every  aspect  of  the  proposition,  although  this 
is  often  difficult,  as  promotors  are  generally  not  willing  to  invest 
money  in  the  preliminary  work  until  the  capital  has  been  pro- 
cured and  construction  work  is  about  to  begin,  yet  the  absence 
of  a  thorough  knowledge  of  all  the  features  involved  in  a  develop- 
ment will  often  necessitates  change  of  plans  during  construction, 
abandonment  of  part  of  the  work  done,  delay  in  completing  the 
plant,  extra  payments  to  the  contractor,  or  lawsuits. 

The  principal  and  often  most  difficult  point  to  be  determined 
is  the  discharge  or  rate  of  flow  of  the  river.  Except  under  very 
favorable  conditions,  a  development  will  only  pay  if  the  whole 
plant  can  be  run  at  all  stages  of  the  water  and  therefore  the  volume 
of  river  discharge,  on  which  the  development  is  based,  should 
be  as  a  rule  the  minimum  low-water  discharge  of  the  average 
year,  although  for  rivers  having  a  widely  varying  minimum  flow 
in  different  years  the  volume  should  be  taken  at  or  near  the  record 
minimum  discharge. 

Next  in  importance  is  the  head,  and  it  is  essential  to  deter- 
mine not  only  the  head  at  low-water  discharge,  but  also  at  times 
of  flood-water  discharge,  as  during  floods  the  tailwater  may  be 
backed  up  to  a  height  of  20  ft.  or  more. 

1  It  is  not  intended  here  to  deal  with  the  physical  aspect  of  the  development 
of  a  water-power  or  the  design  of  dams,  as  these  subjects  are  fully  treated  in 
such  books  as  Merriman,  "Treatise  on  Hydraulics";  Frizell,  "Water-power"; 
Wilson,  " Irrigation  Engineering";  Wegmann,  "Design  and  Construction  of 
Dams ' ' ;  Baker,  ' '  Masonry  Construction ' ' ;  etc. 

180 


THE  DEVELOPMENT.  181 

The  hydraulic  engineer  is  often  required  to  base  his  prelimi- 
nary work  on  measurements  furnished  by  some  unknown  engineer, 
but  such  data  should  only  be  used  with  the  greatest  caution. 
In  his  own  practice  the  writer  found  some  of  the  figures  furnished 
for  the  river  discharge  to  be  from  five  to  nine  times  the  actual  low- 
water  discharge,  and  the  head  given  to  exceed  the  actual  head 
by  25  to  75%.  The  engineer,  when  basing  the  preliminary  work 
on  such  measurements,  which  he  has  no  chance  to  verify,  should 
save  his  own  reputation  by  stating  in  his  report  on  the  proposition : 
According  to  the  measurements  furnished  by,  etc. 

It  will  sometimes  be  found  advisable,  for  economical  reasons, 
to  develop  only  part  of  the  available  head,  as  the  utilization  of 
the  remaining  head  would  increase  the  cost  of  the  plant  per  horse- 
power to  a  disproportionate  extent.  In  general  it  can  be  stated 
that  the  higher  the  head,  the  longer  may  be  the  water-conductors 
that  can  be  used  economically. 

Before  making  any  definite  plans  the  engineer  should,  if  pos- 
sible, visit  the  site  of  the  proposed  development  during  a  spring 
flood,  to  study  the  action  of  the  water,  ice,  etc.,  and  design  his 
dam  and  head-works  accordingly.  The  informations  regarding 
such  action  of  the  spring  flood,  given  by  inhabitants  of  the  locality, 
should  be  accepted  only  with  caution. 

The  engineer  is  also  sometimes  furnished  with  a  map  showing 
elevations  of  the  underlying  rock,  the  soundings  being  made  by 
ramming  down  a  gas-pipe,  but  such  soundings  are  very  unreliable, 
as  the  pipe  will  often  strike  large  boulders  embedded  in  the  earth, 
and  thus  show  an  apparent  elevation  of  the  rock  which  may  be 
considerably  above  the  actual  one. 

When  calculating  the  stability  of  a  bulkhead  or  dam  where  the 
penstock-inlets  are  located,  the  loss  of  weight  in  the  bulkhead 
due  to  the  displacement  of  concrete  or  masonry  by  the  inlets  must 
be  taken  into  consideration;  also,  when  calculating  such  a  bulk- 
head for  crushing  and  shear,  the  reduction  in  the  horizontal 
crushing  and  shearing  area,  at  the  elevation  of  the  center  of  the 
inlets,  must  be  considered. 

The  modern  hydraulic  engineer  should  be  an  expert  in  concrete 
.and  concrete-and-steel  construction. 

The  sand  used  in  mortar-  and  concrete-making  should  be  fre- 


182  WATER-POWER  PLANTS. 

quently  examined,  as  with  the  horizontal  and  vertical  extension 
of  the  sand-pit  its  quality  may  change  quite  suddenly.  Sawdust, 
discharged  into  a  river,  will  usually  cause  the  beach-sand  below 
to  be  intermingled  with  fine  sawdust  of  the  same  color  as  the 
sand.  Such  sawdust,  of  course,  makes  the  sand  unfit  for  mortar- 
or  concrete-making,  but  it  often  requires  a  close  examination  to 
detect  it.  Wood-pulp  refuse,  discharged  into  a  river,  will  also 
frequently  make  the  beach-sand  below  unfit  for  use  and  cover 
the  beach-pebbles  with  fine  films  of  pulp,  but  by  washing  them 
thoroughly  such  pebbles  may  be  employed  in  concrete-making. 

To  prevent  tunnels  and  chambers  in  the  concrete  or  masonry 
foundation  of  a  power-house  from  being  damp,  such  tunnels  and 
chambers  should  be  well  ventilated. 

The  resident  engineer  should  always  endeavor  to  be  on  friendly 
terms  with  the  contractor.  If  the  contractor  meets  with  any 
difficulties  in  his  work,  the  engineer  should  do  all  in  his  power 
to  aid  him  with  his  experience  and  knowledge,  as  the  engineer 
is  likely  to  meet  with  difficulties  on  the  next  day  and  the  con- 
tractor's experience  may  prove  useful  to  him. 


For  preliminary  work  the  power  may  usually  be  calculated 
by  assuming  the  total  efficiency  of  the  development,  and  with 
good  judgment  the  result  should  be  within  5%  of  the  actual 
power.  The  total  efficiency  may  vary  from  about  60%  for 
developments  with  very  long  water-conductors,  low-class  turbines, 
etc.,  to  about  85%  for  developments  with  open  turbine-chambers, 
high-class  turbines,  etc. 

If  Ht  is  the  total  head  utilized,  Q  the  number  of  cubic  feet  of 
water  per  second,  fjt  the  total  efficiency  of  the  development,  and 
62.3  the  weight  in  pounds  of  a  cubic  foot  of  water  at  approximately 
70°  F.,  then  the  horse-power  will  be 


fi2  3  V 

If  the  first  term  of  the  right-hand  side  of  the  equation,  or  — ,_ 

ooU 


THE  DEVELOPMENT.  183 

equals  /,  and  its  reciprocal,  j,  equals  r,  for  the  assumed  total  effi- 
ciency, then  the  horse-power  will  be 


VALUES  OP  /  AND  r  FOR  DIFFERENT  EFFICIENCIES. 

Total  efficiency,  i)t  '•    60%          65%          70%          75%       80%  85% 

/:    0.068        0.074        0.080        0.085      0.091  0.096 

r:14.71         13.58         12.61         11.77       11.03  10.39 

All  important  water-power  plants,  using  large  turbine  units, 
should  be  arranged  to  have  a  separate  head-gate  and  penstock  and 
a  separate  tailrace,  up  to  the  point  where  the  tailrace  emerges  from 
under  the  power-house,  for  each  unit. 

The  head  to  be  considered  in  connection  with  turbines  is,  of 
course,  the  head  available  or  effective  at  the  turbines,  and,  as  a  rule, 
turbines  are  chosen  to  give  their  best  efficiency  with  the  effective 
head  obtained  during  low  water,  but  sometimes  they  are  selected 
for  the  normal  or  average  head. 

If  a  turbine  develops  a  power  E,  under  a  head  of  H  ft.,  uses 
Q  cubic  feet  of  water  per  second  and  runs  at  n  revolutions  per 
minute,  then  the  same  turbine  will,  under  any  other  head  Hr, 
•develop  a  power  Ef,  use  Qr  cubic  feet  of  water  per  second  and  run 
at  n'  revolutions  per  minute,  or 


This  is  provided  the  head  H'  does  not  differ  so  much  from  the  head 
H  that  the  turbine  will  give  different  efficiencies  under  the  two 
heads. 

Engineers  often  appear  to  think  that  it  is  a  special  merit  to 
install  turbines  of  very  large  power,  but  the  horse-power  of  a  turbine 
should  always  be  in  proportion  to  the  capacity  of  the  plant.  Thus 
in  a  plant  of  10,000  H.P.  capacity  it  would  be  wrong  to  install  two 
5000-H.P.  turbines,  as  a  breakdown  would  reduce  the  plant  to  one 
half  of  its  capacity,  \vhile  with  four  2500-H.P.  turbines  a  break- 
down would  reduce  the  capacity  of  the  plant  by  only  25%. 


184  WATER-POWER  PLANTS. 

In  Europe  all  important  plants  which  sell  power  have  a  spare 
turbine  unit,  always  kept  ready  to  set  to  work  should  any  other 
unit  break  down,  and  it  would  be  well  if  this  plan  were  generally 
followed. 

All  turbines  must  have  a  capacity  somewhat  in  excess  of  the 
maximum  load,  to  have  a  margin  for  speed  regulation.  Reaction 
turbines  usually  give  their  best  efficiency  when  discharging  80% 
of  the  amount  of  water  discharged  with  full  gate  opening,  and  it 
is  advisable  to  install  turbines  to  develop  the  ordinary  maximum 
of  power  required  with  this  discharge,  and  to  leave  the  remaining 
20%  of  discharge  for  emergency  loads  and  as  a  margin  for  speed 
regulation. 

In  a  large  plant,  containing  many  turbine  units,,  it  is  not  neces- 
sary for  the  turbines  to  have  a  high  efficiency  with  part  gate,  as 
the  engineer  in  charge  of  the  plant  can  attend  to  the  larger  changes 
in  the  demand  for  power  by  the  starting  and  stopping  of  turbine 
units,  while  one  turbine  unit  takes  care  of  all  minor  fluctuations  in 
the  power  required. 

Some  engineers  think  to  be  very  far-sighted  to  specify  dynamos 
to  be  capable  of  running  for  hours  with  an  overload  of  50%,  and 
thus  the  turbine  necessary  to  utilize  such  an  overload  capacity  is 
required  to  run  with  only  two-thirds  of  its  full  load  and  the  cor- 
responding decreased  efficiency,  during  the  whole  time  that  the 
dynamo  runs  with  its  normal  load.  As  large  dynamos  are  usually 
designed  to  be  capable  of  running  from  two  to  three  hours  with  an 
overload  of  25%,  the  dynamo  with  a  50%  overload  capacity  is,  as 
a  rule,  simply  a  larger-sized  dynamo,  sold  under  the  name  of  a 
smaller-sized  one,  to  suit  the  demand  of  the  engineer.  The  better 
plan  is,  of  course,  to  have  an  extra  turbine  and  dynamo  unit  to 
take  care  of  an  exceptional  or  emergency  load. 

As  already  stated,  special  reaction  turbines  can  be  built  which 
give  their  maximum  efficiency  at  any  desired  gate-opening  and 
corresponding  discharge,  but  such  turbines  do  not  give  as  high  a- 
maximum  and  average  efficiency  as  the  ordinary  turbine.  Turbine 
specifications  should  not  only  state  the  power  which  the  turbine 
is  to  develop  with  full  gate-opening,  but  also  the  maximum  power 
which  will  be  accepted,  as  turbine-builders,  to  obtain  the  desired 
number  of  revolutions,  often  furnish  a  larger  turbine  than  is  other- 


THE  DEVELOPMENT.  185 

wise  necessary,  which  means  that  the  turbine  has  to  run  with  part- 
gate  and  part-gate  efficiency,  even  when  developing  the  maximum 
power  required.  The  amount  of  power  to  be  accepted  in  excess, 
over  the  required  maximum  power,  should  be,  under  ordinary  con- 
ditions, about  20%  for  a  turbine  of  100  H.P.  and  decreasing  to 
about  5%  for  a  turbine  of  5000  H.P. 

In  the  plans  accompanying  turbine  specifications  only  such 
dimensions  should  be  given  as  must  be  adhered  to  for  some  reason 
or  other,  leaving  the  turbine-manufacturer  free  to  choose  the 
dimensions  that  will  best  suit  his  designs  or  patterns. 

The  efficiency  te:ts  of  a  turbine  should  always  be  made  after 
the  turbine  has  been  installed  in  the  plant  in  which  it  is  to  run, 
and  under  normal  working  conditions.  The  turbine  specifications 
should  therefore  state  that  the  efficiency  tests  are  to  be  made  after 
the  turbine  is  installed,  and  how  the  water  and  the  power  are  to  be 
measured.  If  the  water  is  to  be  measured  by  a  weir,  as  is  usually 
the  case,  a  drawing  of  the  weir,  giving  all  important  details  and 
dimensions,  should  accompany  the  turbine  specifications,  to  avoid 
all  disputes  in  this  respect.  As  friction-brakes,  especially  for  large 
powers,  are  rather  expensive,  the  turbine-builder  should  have  on 
hand  different  sizes  of  such  brakes,  and  the  turbine  contract  should 
include  provisions  for  the  loan  of  the  necessary  brake.1 

Where  the  turbine  is  used  for  generating  electric  current,  it 
is  best  to  measure  the  power  developed  by  means  of  the  dynamo 
output;  but,  as  some  turbine  manufacturers  object  to  this,  it  should 
in  such  cases  always  be  stated  in  the  turbine  specifications  that 
the  power  is  to  be  measured  from  the  electric  output.  Of  course, 
if  the  power  of  a  turbine  is  to  be  measured  in  this  manner,  then 
the  dynamo  has  to  be  properly  tested  for  efficiency  before  leaving 
the  shops  of  the  builders,  and  this  is  usually  done  as  follows: 

The  armature-  and  field-windings  of  a  dynamo  are  tested  for 
resistance  and  insulation,  both  while  the  dynamo  is  being  built 
and  after  it  is  completed,  and  the  dynamo  is  then  tested  for  effi- 
ciency by  running  it  at  full  speed  and  with  various  outputs.  The 
power  for  driving  the  dynamo  is  usually  furnished  by  a  motor 


1An  illustrated  description  of  a  hydraulic  friction-brake  for  large  powers 
will  be  found  in  Engineering  News,  May  19,  1904,  p.  474. 


186  WATER-POWER  PLANTS. 

of  known  efficiency,  and  whenever  possible  the  output  of  the 
dynamo  under  test  is  in  turn  used  to  furnish  the  greater  part  of 
the  current  required  by  the  motor.  If  two  or  more  dynamos  of 
equal  size  are  being  built  for  the  same  plant  and  at  the  same  time, 
the  running  tests  are  made  by  setting  two  of  the  dynamos  with 
their  shafts  in  line,  their  coupling  ends  together,  and  coupling 
them.  One  of  the  dynamos  is  then  used  as  a  motor  and  the  other 
as  a  dynamo,  and  the  difference  between  input  and  output,  that 
is  the  amount  of  electric  power  or  watts  required  from  some  out- 
side source,  is  the  power  loss  of  the  combined  motor  and  generator, 
.and  one  half  of  it  is  assigned  to  each  dynamo.  Of  course 
"this  is  not  quite  correct,  as  the  efficiency  of  the  different  dynamos 
may  not  be  the  same,  but  the  difference  in  efficiency  for  large 
generators  will  rarely  exceed  J%. 

While  testing  a  turbine,  the  output  of  the  dynamo  is  usually 
absorbed  by  a  rheostat.  If  the  power  is  very  large  or  no  other 
rheostat  is  on  hand,  a  water-rheostat  is  constructed.  Such  a 
rheostat  consists  of  two  flat  iron  or  steel  plates,  one  laid  horizon- 
tally on  the  bottom  of  the  river  or  a  pond,  and  the  other  sup- 
ported horizontally  above  it  in  the  water,  in  such  a  way  that  it 
may  be  raised  or  lowered.  A  short  circuit  would  be  caused  if  the 
upper  plate  should  accidentally  drop  on  to  the  lower  one,  and  to 
prevent  this  two  scantlings  or  small  timbers  are  laid  on  top  of 
the  lower  plate. 

Each  plate  is  connected  to  one  of  the  poles  of  the  dynamo. 
For  alternating-current  dynamos,  one  set  of  plates  is  required 
for  each  phase.  By  raising  or  lowering  the  upper  plate,  that  is 
by  increasing  or  decreasing  the  distance  between  the  plates,  the 
output  in  amperes  of  the  dynamo  is  decreased  or  increased  respect- 
ively. About  50  amperes  should  be  allowed  per  square  foot  of 
each  plate,  and  the  size  of  the  plates  chosen  accordingly.  If  the 
water  is  very  pure,  the  rheostat  should  be  constructed  in  a  wooden 
tank  or  pond,  or  a  pit  dug  for  the  purpose,  and  salt  added  to  the 
water  to  increase  its  conductivity 

The  power  output  of  the  dynamo  is  measured  by  a  special 
test  watt  meter,  two  such  meters  being  required  for  polyphase 
dynamos.  The  watt  meter  or  meters  should  be  loaned  from 
the  builders  of  the  dynamo,  and  the  dynamo  contract  should 


THE  DEVELOPMENT.  187 

therefore  include  provisions  for  the  loan  of  the  required  test  watt 
meter  or  meters. 

Surface,  Anchor,  and  Frazil  Ice. — With  the  exception  of  some 
of  the  Southwestern  States,  the  greatest  difference  between  high- 
and  low-water  discharge  of  North  American  rivers  is  to  be  found 
in  the  northern  parts  of  the  United  States  and  in  Canada,  that  is 
in  localities  having  a  long  and  severe  winter,  the  reason  being 
that,  while  there  is  usually  an  abundant  amount  of  rainfall  during 
the  summer,  nearly  the  whole  of  the  precipitation  during  the 
winter  is  in  the  form  of  snow,  of  which  by  far  the  greater  part 
accumulates  until  the  warm  weather  sets  in,  when  the  whole 
accumulation  runs  off  in  a  comparatively  short  tune,  thus  form- 
ing the  spring  floods. 

Northern  rivers,  like  those  located  farther  south,  have  a  period 
of  low  water  during  the  dry  season,  that  is  in  August  or  the  first 
half  of  September,  but  the  lowest  water  of  the  year  occurs  usually 
during  the  latter  half  of  February  and  the  first  half  of  March, 
being  due  to  the  accumulation  of  the  precipitation  and  the  re- 
taining of  part  of  the  water  in  rivers  and  lakes  in  the  form  of 
ice. 

For  rivers  having  a  drainage  area  of  500  square  miles  and  over, 
the  average  discharge  during  the  period  of  winter  low  water  may 
be  considered  to  be  one  half  of  a  cubic  foot  per  second  per  square 
mile  of  drainage  area,  but  often  is  less  in  certain  rivers  or  in  winters 
of  great  severity,  as  will  be  seen  from  the  figures  given  here  for 
three  rivers  of  the  Province  of  Quebec,  the  discharge  being  meas- 
ured with  current-meters  through  holes  cut  into  the  ice. 

St.  Maurice  River:  flowing  north  to  south;  drainage  area  18,000 
square  miles,  almost  entirely  covered  by  forest ;  winter  low-water 
discharge  7515  cu.  ft.,  or  0.418  cu.  ft.  per  second  per  square  mile. 

Chaudiere  River:  flowing  east  to  west;  drainage  area  2600 
square  miles,  almost  entirely  denuded  of  forest;  winter  low-water 
discharge  620  cu.  ft.,  or  0.24  cu.  ft.  per  second  per  square  mile. 

Metabetchouan  River:  flowing  south  to  north;  drainage  area 
890  square  miles,  entirely  covered  by  forest ;  winter  low- water  dis- 
charge 380  cu.  ft.,  or  0.43  cu.  ft.  per  second  per  square  mile. 

On  account  of  the  floating  ice  it  is  almost  impossible  to  make 
even  approximate  measurements  of  the  river  discharge  during 


188  WATER-POWER  PLANTS. 

the  spring  high  water,  except  where  an  overflow-dam  exists,  as 
is  the  case  on  the  Chaudiere  River.  From  the  records  kept  by 
the  owner  of  this  dam,  the  spring  high-water  discharge  in  certain 
years  has  been  as  much  as  121,000  cu.  ft.,  or  46.54  cu.  ft.  per  second 
per  square  mile,  that  is  195  or  practically  200  times  the  amount 
of  low- water  discharge.  In  this  case  the  great  difference  between 
high-  and  low-water  discharge  is  partly  due  to  the  fact  stated 
above,  that  the  drainage  area  is  almost  denuded  of  forest.  The 
influence  of  the  forest  during  the  spring  high-water  season  con- 
sists chiefly  in  the  retardation  of  the  thawing  of  the  snow  and 
ice.  In  the  forests  snow  may  still  be  lying  to  a  depth  of  3  ft., 
while  in  the  open  country  it  has  almost  entirely  disappeared. 

The  period  of  winter  low  water  is,  of  course,  very  unfavorable 
for  water-power  electric  plants  supplying  light,  as  the  lowest  water 
occurs  at  a  time  when  the  demand  for  light  is  nearly  at  its  maximum. 

In  cold  climates  the  greatest  care  and  judgment  are  required 
in  designing  a  water-power  development,  as  the  pressure  of  the  ice, 
both  of  the  sheet  as  formed  and  of  accumulations  of  floating  ice- 
floes, is  often  tremendous,  and  the  chief  aim  of  the  engineer  should 
always  be  to  prevent  the  ice  from  reaching  and  exerting  its  pres- 
sure upon  the  structures  of  a  development.  While  the  stationary 
sheet  or  surface  ice  rarely  gives  trouble,  the  accumulations  of  ice- 
floes often  become  very  dangerous. 

Where  the  ice  goes  out  at  or  near  the  highest  stage  of  the  spring 
flood-water,  as  is  mostly  the  case,  the  conditions  are  the  most 
favorable.  Where  the  ice  or  part  of  it  goes  out  after  the  spring 
flood,  danger  can  be  averted  in  most  instances ;  but  where  the  ice  or 
a  large  part  of  it  comes  down  the  river  before  the  spring  high  water 
has  arrived,  conditions  usually  are  dangerous. 

Most  head-works  of  a  development  obstruct  the  river  channel 
to  some  extent,  especially  a  dam  across  the  river;  and  with  the  ice 
arriving  without  sufficient  water  to  carry  it  around  or  over  such 
obstructions,  accumulations  will  be  formed  so  fast  that  even  a 
large  ice-sluice  and  the  liberal  use  of  dynamite  cannot  prevent  a 
serious  ice- jam.  When  high  water  sets  in  and  finds  the  channel 
blocked  by  ice,  it  rises  rapidly,  flooding  the  surrounding  country, 
until  the  hydraulic  head  has  increased  sufficiently  to  produce  an 
ice-shove,  that  is  a  down-stream  movement  of  the  whole  accumu- 


THE  DEVELOPMENT.  189 

lation  in  a  body,  carrying  before  it  guide-booms  and  cribs  and 
perhaps  the  whole  head-works  of  the  development. 

The  direction  of  the  wind  is  often  a  very  important  factor  in  the 
formation  of  an  ice- jam. 

When  an  overflow-dam  is  to  be  built  across  a  river  in  which 
ice-jams  occur,  a  dam  section  having  a  vertical  up-stream  face 
should  be  avoided.  The  triangular  cross-section,  so  frequently 
used  for  timber  dams,  having  both  up-  and  down-stream  face 
inclined  to  form  an  angle  of  about  30°  with  the  horizontal,  is  per- 
haps the  best  that  can  be  chosen,  as  with  such  a  section  the  ice 
cannot  exert  pressure  against  the  face,  but  will  be  forced  up  the 
incline  and  over  the  crest  and  then  shoot  down  the  lower  face  and 
away  from  the  toe. 

Dams  with  a  vertical  or  nearly  vertical  up-stream  face  should 
be  provided  with  an  apron  starting  from  the  top  of  the  up-stream 
face  and  sloping  downward  at  an  angle  of  about  30°.  Such  aprons 
are  usually  built  of  timber,  with  only  the  upper  part  covered  by 
planks,  and  serve  the  same  purpose  as  the  inclined  up-stream  face 
of  a  timber  dam. 

The  down-stream  toe  of  overflow-dams  is  in  all  cases  to  be 
well  protected  from  the  impact  of  the  ice  coming  over  the  dam; 
especially  masonry  dams  with  ogee-shaped  down-stream  face  are 
very  liable  to  have  the  lower  part  of  the  ogee  curve  knocked  off. 

High  overflow-dams  should  be  avoided  where  possible,  and  a 
low  dam  and  penstock  used  instead,  even  if  the  first  cost  is  greater 
and  a  close  speed  regulation  of  Jthe  turbines  made  more  difficult. 

Earth  dams  or  embankments  should  be  kept  out  of  reach  of  the 
floating  ice,  as  large  floes  will  cut  through  any  slope-paving  and 
thus  may  cause  the  destruction  of  an  earth  dam. 


Surface  ice  on  fast-flowing  rivers  is  formed  as  bordage  ice,  that 
is  by  starting  along  the  shore  and  extending  outward.  Surface 
ice  on  stationary  bodies  of  water,  such  as  lakes,  etc.,  or  on  slowly 
flowing  rivers,  begins  with  the  formation  of  needle-crystals  all 
over  the  surface  wrhich,  increasing  in  number  and  size  and  freezing 
together,  form  the  surface  sheet.  Surface  ice  grows  by  being 
cooled  below  the  freezing-point  and  abstracting  latent  heat  from 


190  WATER-POWER  PLANTS. 

the  water  in  contact  with  its  lower  side,  which  causes  such  water 
to  freeze  to  the  surface  ice.  The  regular  surface  ice  will  rarely 
grow  to  a  thickness  of  over  3  or  4  ft.,  but  anchor-ice  and  frazil, 
where  such  is  formed,  is  carried  below  the  surface  ice  and,  adhering 
in  great  quantities  to  the  lower  side  of  it,  will  increase  its  thick- 
ness by  freezing  to  it.  In  this  manner  the  surface  ice  may  in- 
crease to  20  ft.  in  thickness,  being  often  solid  to  the  very  river 
bottom.  In  the  St.  Lawrence  River  the  anchor-ice  and  frazil 
at  times  form  masses  hanging  from  the  surface  ice  to  a  depth 
of  80  or  90  ft.  below  the  water  level. 

In  the  United  States  it  is  generally  supposed  that  the  terms 
anchor-ice  and  frazil  are  synonymous,  and  this  mistake  is  even  to 
be  found  in  dictionaries;  but  anchor-ice  and  frazil  are  actually 
two  entirely  different  formations.  The  Montreal  flood  commission, 
which  may  be  regarded  as  an  authority  on  the  subject,  says  in  its 
report,  printed  in  1890:  "Frazil,  as  distinguished  from  anchor-ice, 
is  formed  over  the  whole  unfrozen  surface  [of  the  St.  Lawrence 
River]  above  and  below  Lachine  Rapids,  between  Prescott  and 
tide-water  and  wherever  there  is  sufficient  current  or  wind  agitation 
to  prevent  the  formation  of  bordage-ice." 

As  it  is  of  importance  to  the  hydraulic-power  engineer  to  fore- 
see what  he  may  have  to  contend  with  in  the  way  of  ice  formation 
in  any  particular  locality,  the  writer  has  given  here  the  causes 
and  principles  of  the  formation  of  anchor-ice  and  frazil.1 

Anchor-ice  is  formed  along  the  bottom  of  rivers,  creeks,  canals, 
and  lakes  of  not  over  30  to  40  ft.  in  depth,  and  is  of  granular  and 

1  Mostly  from  reports  on  the  investigations  made  under  the  direction  of 
Prof.  Callendar  of  McGill  University,  Montreal,  Que.  by  Dr.  H.  T.  Barnes,  of 
McGill  University.  These  investigations  were  carried  on  during  the  winter 
•of  1895  to  1896  at  a  place  opposite  Montreal,  taking  the  water  temperatures 
through  holes  cut  into  the  ice,  and  during  the  winter  of  1896  to  1897  in  the  open 
water  of  the  Lachine  Rapids.  The  temperatures  were  measured  by  an  elec- 
trical thermometer  with  platinum  resistance,  indicating  differences  of  0.0001 
of  a  degree  Centigrade,  when  used  with  laboratory  facilities  while  in  the  field 
its  accuracy  could  be  relied  on  to  0.001°  C.  These  reports  will  be  found 
in  part  in  the  Trans.  Can.  Soc.  C.  E.,  vol.  15,  1901,  pp.  78  to  95. 

See  also  "Experience  with  Anchor-ice  at  the  Detroit  Water- works  and 
Elsewhere,"  by  C.  W.  Hubbell,  in  The  Michigan  Technic,  University  of 
Michigan,  1903;  also  in  Engineering  News,  Aug.  13, 1903,  p.  147. 


THE  DEVELOPMENT.  191 

porous  texture  and  of  little  strength.  The  formation  of  anchor-ice 
is  caused  by  the  radiation  of  heat  from  the  river  or  lake  bottom 
into  space,  the  radiation  taking  place  through  the  water  and  the 
atmosphere  and  even  through  thin,  clear  ice.  The  river  or  lake 
bottom,  cooled  below  the  freezing-point  and  abstracting  latent 
heat  from  the  water  in  contact  with  it,  causes  such  water  to  freeze 
to  the  bottom.  The  radiation  of  heat  through  the  ice  was  demon- 
strated by  Professor  TyndalL,  who  brought  platinum  to  red  heat  by 
concentrating  the  sun's  rays  through  a  lens  made  of  ice.  After 
the  anchor-ice  has  commenced  to  form,  the  heat  from  the  river- 
bottom  is  radiated  through  the  anchor-ice  or  conducted  through 
it  and  radiated  from  the  surface  of  the  anchor-ice,  causing  the 
anchor-ice  to  grow  in  thickness. 

Conditions  favorable  to  the  formation  of  anchor-ice  therefore 
are  a  clear  cold  night,  shallow  open  water  or  shallow  water  only 
covered  with  a  thin  clear  ice-sheet.  The  radiation  of  heat  from 
the  river  bottom  into  space,  and  with  it  the  formation  of  anchor- 
ice,  is  partly  or  wholly  prevented  by  cloudy  weather,  thick,  rough 
or  granular  surface  ice  and  heavy  snow  on  the  surface  ice,  while 
bright  sunshine,  striking  the  river  bottom,  counteracts  the  radia- 
tion of  heat  and  thus  also  prevents  the  formation  of  anchor-ice. 
When  anchor-ice  grows  thick  it  will,  owing  to  its  granular  tex- 
ture, retard  or  entirely  prevent  the  radiation  or  conduction  of 
heat  through  it,  and  further  heat,  being  conducted  from  the  interior 
of  the  earth  to  the  surface  of  the  river  bottom,  will  melt  off  the 
hold  of  the  anchor-ice.  This  melting  off  will  also  occur  when 
the  sun's  rays  penetrate  through  the  water  to  the  anchor-ice, 
thus  causing  the  anchor-ice  to  appear  on  the  surface  of  the  water 
when  the  sun  is  high  and  warm.  During  the  investigations  it 
was  found  that  the  thermometer  while  in  the  water  would  show 
a  higher  temperature  than  the  water  itself  when  struck  by  the 
sun's  rays. 

In  lakes  and  gently  flowing  rivers  the  warmer  water,  owing 
to  its  specific  gravity,  which  is  greatest  at  39°  F.,  sinks  to  the 
bottom,  and  no  anchor-ice  can  therefore  be  formed  until  the  whole 
body  of  the  water  has  been  uniformly  cooled  to  the  freezing-point. 

However  the  amount  of  anchor-ice  formed  by  radiation  from 
the  river  bottom  is  only  small,  but  this  amount  may  bs  rapidly 


192  WATER-POWER  PLANTS. 

increased  by  frazil  adhering  and  freezing  to  the  anchor-ice,  often 
producing  branching  or  tree-shaped  formations  of  ice,  which 
grow  further  by  entangling  surface-formed  ice  carried  down  by 
the  current. 

The  formation  of  frazil  or  needle-ice  takes  place  in  rapids,  where 
the  velocity  or  agitation  of  the  water  prevents  the  formation  of 
surface  ice.  With  the  temperature  of  the  air  much  below  the 
freezing-point,  the  churning  water  becomes  slightly  undercooled, 
that  is  it  falls  to  a  temperature  not  exceeding  0.01°  C.  below  the 
freezing-point.  This  undercooling  extends  to  the  depth  to  which 
the  water  is  agitated,  and  throughout  this  depth  frazil  is  formed 
in  needle-shaped  crystals. 

These  crystals  are  usually  formed  around  minute  particles  of 
material  suspended  in  the  water,  which  grow  colder  than  the 
water  itself  by  radiation,  and  act  as  a  nucleus  or  starting-point 
for  the  crystals. 

The  size  of  the  frazil  crystals  is  the  larger  the  less  the  velocity 
or  agitation  of  the  water  is  and  the  more  it  is  undercooled,  varying 
from  the  size  of  a  small  darning-needle  to  the  size  of  an  ordinary 
lead  pencil;  also,  the  more  the  water  is  undercooled  the  greater 
is  the  amount  of  frazil  formed,  and  this  formation  may  be  so  great 
that  the  water  will  become  like  a  thin  paste  and  have  a  dull  sandy 
color. 

Frazil  is  very  sticky  while  the  water  is  undercooled,  and  will 
adhere  and  freeze  to  surface  ice  and  to  any  other  object  it  comes 
in  contact  with.  However,  the  greatest  trouble  is  caused  by  the 
frazil  crystals  freezing  to  each  other  and  to  floating  anchor-ice, 
forming  lumps  or  agglomerations  of  ice,  which  cannot  be  stopped 
by  glance  booms  and  are  capable  of  choking  anything  from  a  tur- 
bine-bucket to  a  head-  or  tail-race. 

Rapids  above  a  water-power  plant  have  the  advantage  that 
they  will  break  up  the  large  floes  of  surface  ice,  which  might  damage 
the  dam  or  head-works  of  the  development,  but  the  choking  of 
-the  water-conductors,  often  requiring  part  of  the  river-flow  for 
scouring  to  keep  these  conductors  clear,  and  the  backing  up  of 
the  tailwater  caused  by  the  accumulations  of  anchor-ice  and 
frazil,  at  a  time  when  the  river-flow  is  at  its  lowest  stage,  are  seri- 
ous disadvantages.  At  one  large  Canadian  water-power  plant 


THE  DEVELOPMENT.  193 

the  effective  head  is  often  reduced  from  11  ft.  to  6  ft.  or  less.  At 
times  30%  of  the  waterway  of  the  St.  Lawrence  River  is  blocked 
by  agglomerations  of  anchor-ice  and  frazil,  and  the  amount  of 
such  ice  in  the  river  is  as  great  as  the  amount  of  the  water  itself. 

In  water  which  is  little  agitated  anchor-ice  and  frazil  rises  and 
freezes  to  the  lower  side  of  the  surface  ice. 

The  only  feasible  way  in  which  to  reduce  or  prevent  the  for- 
mation of  anchor-ice  and  frazil  is  to  drown  out  the  rapids  by  the 
building  of  a  dam,  so  that  continuous  surface  ice  will  be  formed 
for  many  miles  above  the  water-power  plant. 

Measurement  of  Water  for  Selling  Water-power. — Where- 
ever  the  owners  of  a  water-power  are  selling  power  in  the  form 
of  water  under  a  head,  that  is  power-water,  some  means  have 
to  be  employed  to  measure  the  amount  of  water  taken  by  the  user. 
No  great  refinement  is  required  in  these  measurements,  but  the 
apparatus  must  be  simple,  so  that  the  readings  may  be  taken  by  a 
man  of  ordinary  intelligence.  Of  the  means  employed  for  such 
measurement,  the  following  have  been  used  to  a  greater  or  less 
•extent : 

1.  Turbine   regulating-gates.     The   turbines    to   be   used    are 
tested  in  a  testing-flume  or  in  place  after  being  installed,  for  the 
.amount  of  water  discharged  with  different  gate-openings  and  with 
the  normal  head  or,  should  the  head  be  very  variable,  with  different 
heads,  between  the  possible  minimum  and  maximum,  under  which 
the  turbines  are  to  be  operated.     A  scale  is  attached  to  each 
turbine,  showing  the  gate-opening,  and  this  scale  is  read  at  reg- 
Har  intervals  of  a  few  hours  by  an  employee  of  the  owners  of  the 
power.    With  variable  heads  gage  readings,  giving  the  head,  are 
taken  at  the  same  time. 

The  turbine  regulating-gates  are  by  far  the  most  widely  employed 
means  for  measuring  power-water. 

Where  the  power  is  used  for  generating  electric  current,  record- 
ing wattmeters  will  at  once  show  the  output  in  electric  power,  and 
from  these  records  and  the  previously  determined  efficiency  of 
the  turbines  and  dynamos  the  amount  of  power-water  used  during 
a  day,  week,  or  month  can  readily  be  ascertained. 

2.  Water-meter  in  by -pass.    The  meter  is  placed  in  a  by-pass  to 
reduce  the  size  of  the  meter,  to  prevent  stoppage  of  main  pipe  or 


ft  of  c 

JCr/.rr  ,  mr 


194  WATER-POWER  PLANTS. 

penstock,  when  the  meter  is  clogged  or  rendered  inoperative,  and 
to  reduce  the  great  friction  and  consequent  loss  of  head  caused  by 
the  meter.  This  method  is  hardly  advisable  for  measuring  water 
in  connection  with  water-powers  for  several  reasons,  namely: 
The  ratio  of  meter-readings  to  actual  flow  in  main  pipe  varies 
very  much,  according  to  the  type  of  meter,  velocity  of  flow  in  main 
pipe,  and  condition  in  which  the  meter  is  kept.  No  reliable  figures 
are  on  hand  for  this  ratio  for  large  pipes.  With  a  ratio  of  meter 
diameter  to  pipe  diameter  as  1 : 3,  the  error  in  measurement  rises 
to  6.5%,  which  would  be  increased  as  this  ratio  is  increased.  A 
screen,  to  protect  the  meter  from  clogging,  could  be  placed  in  such 
a  way  that  all  solid  matter,  as  chips,  bark,  etc.,  will  go  past  it,  but 
grass  and  other  fibrous  matter  will  .soon  cover  the  screen  with  a 
felty  layer.  No  direct  reading  can  be  made  for  a  day's  or  week's 
flow,  as  the  ratio  of  meter  reading  to  actual  flow  in  main  pipe 
varies  so  much,  being,  for  example,  2.1  for  a  flow  of  2.7  cu.  ft., 
and  2.8  for  a  flow  of  84.5  cu.  ft.  per  minute;  therefore  the  flow 
can  only  be  obtained  by  taking  the  movement  of  the  meter  for, 
say,  one  minute,  from  which  the  actual  flow  for  this  particular 
minute  may  be  calculated.  Each  meter  has  to  be  carefully  tested 
in  connection  with  its  main  pipe  for  all  speeds  of  water.  In  cold 
weather  the  meter  has  to  be  protected  against  freezing.  A  Venturi 
meter  can  be  substituted  for  the  ordinary  water-meter,  thus  avoid- 
ing all  moving  parts.  Frazil  may  choke  the  by-pass  entirely. 

3.  Pitot  gage.  This  meter  consists  of  two  tubes  inserted  into 
the  penstock,  one  giving  the  static,  the  other  the  static  plus  the 
impact  or  velocity  head,  the  difference  of  head  indicating  the 
velocity  of  the  flow  and  thus  the  actual  flow.  Each  tube  is  pro- 
vided with  a  float,  the  float  in  the  static  pipe  carrying  the  scale 
and  the  float  in  the  impact  pipe  carrying  a  rod  with  an  index.  By 
arranging  the  scale  properly,  the  velocity  or  volume  of  flow  can 
be  read  at  any  moment,  and  a  recording  apparatus  can  be  attached 
showing  the  mean  and  total  flow  for  a  day,  week,  or  month.  Veloci- 
ties as  low  as  4  ins.  per  second  are  indicated,  and  the  error  is  said 
not  to  exceed  3%.  The  pipes  can  be  made  large  enough  so  they 
cannot  be  clogged  by  small  floating  matter.  The  pipes,  however, 
reaching  into  the  middle  of  the  penstock,  are  an  impediment  to 
the  water,  and  large  pieces  of  wood,  bark,  etc.,  which  may  enter 


THE  DEVELOPMENT.  195 

the  penstock  through  places   where  the  rack-bars  have  bent  or 
spread,  may  make  the  gage  inoperative.1 

In  cold  weather  the  tubes  have  to  be  protected  against  freezing 
and  the  lower  ends  are  liable  to  be  choked  by  frazil. 

4.  Venturi  meter.     This  meter  consists  of  two  cones,  jointed 
at  their  small  end  by  a  throat-piece.    The  difference  of  pressure 
between  large  cone  ends  and  throats  indicates  the  velocity  and 
volume  of  flow  at  any  moment,  and  a  recording-apparatus  can  be 
attached  showing  the  mean  and  total  flow  for  a  day,  week,  or  month. 
The  error  is  said  not  to  exceed  2%.     With  this  meter,  however, 
the  accuracy  depends  on  the  exact  size  of  the  throat,  and  this  will 
be  soon  enlarged  by  the  sand  carried  in  the  water.     The  small 
connections  between  air-chamber    and  throats  are  likely   to  be 
clogged.     For  large  quantities  of  water  the  price  of  the  meter  is 
very  high  and  the  size  is  enormous.    By  reducing  the  size,  to  lessen 
the  price  of  the  meter,  the  loss  of  head  is  rapidly  increased. 

In  cold  weather  the  throat  and  air-chamber  have  to  be  protected 
against  freezing.  The  connections  between  throat  and  air-chamber 
are  liable  to  be  choked  by  frazil. 

5.  Measuring-gate.    The  meter  consists  of  a  gate  with  opening 
set  and  kept  in  a  fixed  position  to  pass  the  amount  of  water  con- 
tracted for.    The  opening  must  be  under  low-water  level  on  the 
up-stream  side.    A  float,  protected  by  a  box,  is  provided  on  both 
the  up-stream  and  the  discharge  side  of  the  gate,  one  carrying  a 
scale,  the  other  a  rod  with  an  index.     By  arranging  the  scale 
properly,  the  velocity  or  volume  of  flow  can  be  read  at  any  moment, 
and  a  recording-apparatus  can  be  attached  showing  the  mean  and 
total  flow  for  a  day,  week,  or  month.     Low  velocities  will  be  indi- 
cated and  the  error  will  not  exceed  2%.     With  this  meter,  however, 
a  correction  has  to  be  made  when  the  gate-opening  is  submerged 

xFor  a  paper  on  the  Pitot  gage  see  "Pitot  Tubes;  with  Experimental 
Determinations  of  the  Form  and  Velocity  of  Jets,"  by  J.  E  Boyd  and  H. 
Judd,  read  before  Section  D  of  the  Am.  Assoc.  for  the  Advancement  of  Science, 
Dec.  29,  1903;  also  reprinted  in  Engineering  News,  March  31,  1904,  p.  318. 

For  a  description  of  a  Pitot  gage  with  recording  apparatus  see  "The  Cole- 
Flad  Photo-Pitometer  and  its  Use  in  Studying  Water  Consumption  and  Waste," 
in  Engineering  News,  Feb.  5,  1903,  p.  130;  also  papers  on  the  same  apparatus, 
by  Edw.  S.  Cole,  in  Trans.  Am.  Soc.  C.  E.,  vol.  47,  p.  275  (1902);  and  Jour. 
Western  Soc.  C.  E.,  vol.  7,  p.  574  (1902). 


196  WATER-POWER  PLANTS. 

on  the  discharge  side,  the  flow  with  wholly  submerged  opening 
being,  according  to  Weisbach,  98.67%  of  the  flow  when  opening 
is  wholly  above  water  on  discharge  side.  This  is  a  reduction  of 
flow  equal  to  67  H.P.  in  5000  H.P.  If  the  gate-opening  is  just 
large  enough  to  pass  the  water  contracted  for,  a  compensating 
reservoir  -  is  required  between  gate  and  penstock  entrance,  for 
temporary  overloads.  This  can  be  avoided  by  making  the  gate- 
opening  large  enough  to  pass  all  the  water  required  at  times  of 
greatest  possible  overload.  Where  the  locality  is  favorable,  a 
measuring-weir  in  the  tailrace  may  be  used,  instead  of  the  gate 
above  the  turbines. 

The  float-boxes  have  to  be  prevented  from  freezing. 

With  all  the  above  devices,  the  actual  head  can  be  taken  into 
consideration  when  figuring  the  horse-power  used. 

All  recording-devices  have,  of  course,  to  be  protected  from  the 
weather  and  extreme  cold. 

Cost  of  Water-power. — Whenever  the  development  of  a  water- 
power  for  the  purpose  of  selling  water  or  mechanical  or  electrical 
energy  is  under  consideration,  the  most  important  question  to 
be  decided  is:  What  is  the  limit  of  cost  per  horse-power  that 
may  be  expended  for  a  development  and  still  leave  the  plant  a 
financial  success,  or  what  is  a  reasonable  price  to  be  charged  per 
horse-power  .per  year? 

A  great  amount  of  data  has  been  published  in  regard  to  the 
cost  of  hydraulic  power  and  power-plants,  but  as  water-powers 
present  an  infinite  variety  of  conditions,  such  prices  of  other 
plants  should  only  be  used  with  the  greatest  precaution.  A  few 
general  figures,  intended  to  apply  to  conditions  at  present  pre- 
vailing in  the  northern  part  of  the  United  States  and  in  Canada, 
may  be  given  here. 

A  water-power  electric  plant,  including  transmission  line  and 
substation,  where  such  are  required,  but  without  the  local  dis- 
tribution, should  not  cost  more  than  $100  per  electrical  horse- 
power if  situated  in  a  remote  location  or  in  a  farming  district; 
but  $150  to  $200  may  be  expended  per  electrical  horse-power  for 
power-plant,  transmission,  and  substation,  if  the  power  can  be 
sold  in  a  large  city  or  industrial  district. 

The  price  charged  for  power-water  per  gross  horse-power  per 


THE  DEVELOPMENT.  197 

year,  delivered  at  or  near  the  customer's  turbines,  may  be  taken 
at  from  $5  to  $15,  the  lower  figure  being  for  remote  locations, 
low  heads,  and  large  powers,  and  vice  versa.  The  price  of  $15 
to  $25  per  mechanical  horse-power  per  year  at  the  power-house, 
or  of  $25  to  $50  per  electrical  horse-power  per  year  delivered  to 
the  customer,  may  be  taken  as  the  limits  paid  at  present.  Here, 
again,  the  lower  price  is  for  remote  locations  and  large  powers, 
and  vice  versa. 

It  is  also  safe  to  state  that  in  a  climate  such  as  that  of  the 
northern  part  of  the  United  States  and  in  Canada,  with  its  long 
and  severe  winters,  it  does  not  pay  to  develop  a  water-power  if 
the  power  produced  will  cost  more  than  75%  of  the  amount  for 
which  steam-power  could  be  produced  in  the  same  locality. 

In  Canada,  with  the  great  number  of  water-powers  yet  un- 
developed or  only  partly  utilized,  it  must  be  regarded  as  poor 
policy  to  install  a  larger  plant  than  can  be  run  at  all  stages  of 
the  water,  or  to  have  a  great  proportion  of  power  dependent 
upon  storage  lakes  during  the  months  of  low  water. 

A  water-power  requiring  an  auxiliary  steam-plant  during  the 
low-water  season  can  only  pay  if  either  the  cost  of  the  develop- 
ment is  exceptionally  low  or  the  locality  very  favorable  for  the 
sale  of  power  or  both.  4 

It  may  be  noted  here  for  comparison  that  in  large  steam- 
power  electric  plants  in  the  Eastern  and  Central  States  the  cost 
of  the  coal  forms  60%  of  the  total  cost  of  the  electric  current.1 

1  According  to  Mr.  H.  G.  Stott,  in  the  discussion  of  M.  P.  Junkersfeld's 
paper  "Multiple  versus  Independent  Operation  of  Units  and  Central  Stations," 
before  the  Am.  Inst.  E.  E.,  April  24,  1903. 


BRITISH  AND  METRIC  MEASURES   AND 
VALUES. 


British  and  Metric  Measures  and  Values. — Below  are  given 
the  more  important  measures  and  values  used  in  hydraulic-power 
engineering,  according  to  both  the  British  and  the  metric  system, 
as  some  of  the  illustrations  shown  here  contain  metric  dimensions 
and  as  the  American  engineering  press  sometimes  prints  accounts 
and  illustrations  of  turbines  or  water-power  developments  taken 
from  German  or  French  contemporaries,  and  also  for  the  con- 
venience of  those  studying  German  or  French  works  on  turbines 
or  hydraulic-power  engineering  or  wish  to  look  up  the  German 
books  and  periodicals  referred  to  in  the  foot-notes. 

While  most  text-books  give  the  equivalents  to  more  decimals, 
the  writer  has  found  the  figures  given  below  sufficiently  accurate 
for  all  practical  purposes. 

When  using  metric  formulae  for  the  design  of  machinery,  the 
writer  has  found  it  very  convenient  to  have  a  four-foot  folding 
rule,  divided  to  inches  and  sixteenths  on  one  side  and  to  centi- 
meters and  millimeters  on  the  other.  By  holding  the  rule  in 
the  hand  and  placing  the  thumb-nail  on  the  edge,  in  line  with 
the  dimension  to  be  converted,  the  equivalent  may  at  once  be 
read  on  the  other  side  of  the  rule.  With  rules  having  the  sub- 
divisions at  opposite  edges,  a  straight  strip  of  writing-paper,  folded 
across  the  two  faces  or  around  the  rule,  will  enable  one  to  read  the 
equivalents  in  a  similar  manner.  This  method  is  sufficiently 
accurate  to  read  to  one  thirty-second  of  an  inch  or  to  one  milli- 
meter. 

199 


200        BRITISH  AND   METRIC  MEASURES  AND  VALUES 

1  foot =0.305  meter.     1  inch =25.4  millimeters. 
1  meter =3.28  feet  =  39.37  inches  =  39f  inches. 
1  mile  =  5280  feet  =1.61  kilometers. 
1  kilometer  =  3281  feet  =0.621  mile. 


1   square  foot  =  0.093  square  meter.     1   square  meter  =10.76 
lare  feet. 
1    square   mile = 
=  0.386  square  mile. 


square  teet. 

1    square   mile =2.59   square   kilometers.     1  square  kilometer 

=  0  38fi  smiflTp  rnilp 


1  cubic  foot  =  0.0283  cubic  meter =28. 32  cubic  decimeters. 
1  cubic  decimeter  =1  liter =0.0353  cubic  foot.     1  cubic  meter 
=  35.3  cubic  feet. 

1  pound  =  0.454  kilogram.     1  kilogram =2.2  pounds. 

1  ton  of  2000  pounds  =  0.9072  metric  ton =907.2  kilograms. 

1  metric  ton  =1000  kilograms  =  2204.6  pounds. 

Weight  of  1  cubic  foot  of  water  at  approximately  70°  F.  or 
21°  C.  =  62.3  pounds.  1  cubic  decimeter  of  water  at  approximately 
21°  C.  =  0.998  kilogram. 

Weight  of  distilled  water  at  4°  C.  =  39°  F. 

1  cubic  decimeter  =1  kilogram.  1  cubic  meter  =1  metric 
ton. 

1  metric  or  mechanical  atmosphere  =1  kilogram  per  square 
centimeter  =14.2  pounds  per  square  inch  =  height  of  barometer 
73.5  centimeters  =  29  inches. 

1  atmosphere  =1.0333  kilogram  per  square  centimeter  =14.7 
pounds  per  square  inch = height  of  barometer  76  centimeters 
=  30  inches. 

Theoretical  height  of  suction  at  sea-level =34  feet  =10.33 
meters. 

1  foot-pound  =  0.1 383  meter  kilogram. 

1  meter  kilogram =7.233  foot-pounds. 

1  British  horse-power  =550  foot-pounds  per  second  =1.014 
metric  horse-power. 

1  metric  horse-power =75  meter-kilograms  per  second =0.986 
British  horse-power. 


BRITISH  AND  METRIC  MEASURES  AND  VALUES.        201 

Acceleration  of  gravity =g— 32.16  feet=9.81  meters. 
\/2g=8.Q2  for  British  and  =4.43  for  metric  measure. 

1  cubic  foot  per  square  mile  =10. 93  liters  per  square  kilometer. 
1   liter  per  square  kilometer =0.0915  cubic  foot  per  square 
mile 

Weight  of  bars,  structural  shapes,  etc. 

1  pound  per  foot  =1.488  kilograms  per  meter. 
1  kilogram  per  meter =0.672  pound  per  foot. 


APPENDIX. 


ELEMENTS  OF  DESIGN  FAVORABLE  TO  SPEED  REGU- 
LATION  IN   PLANTS  DRIVEN  BY  WATER-POWER. 

A  paper  presented  at  the  16th  General  Meeting  of  the  American  Institute  of 
Electrical  Engineers,  Boston,  June  27th,  1899. 

By  ALLAN  V.  GARRATT. 

In  this  paper  the  writer  will  endeavor  to  describe  those  pecu- 
liarities of  design  of  plant  which  have  a  special  bearing  on  speed 
regulation,  but  no  attempt  will  be  made  to  discuss  the  theory, 
mechanical  construction,  or  merits  of  the  various  water-wheel 
governors  on  the  market. 

The  engineer  is  often  confronted  with  the  problem  of  design- 
ing a  plant  upon  an  undeveloped  or  partly  developed  water-power, 
and  the  desired  end  is  to  come  out  with  a  plant  of  good  mechanical 
and  electrical  design  and  yet  have  it  such  that  the  speed  of  the 
electrical  apparatus  may  be  maintained  within  comparatively 
close  limits  under  any  load  variations  which  can  possibly  occur, 
and  to  maintain  the  speed  within  very  close  limits  under  any 
working-load  variations. 

The  kind  of  generating  apparatus  used,  and  the  nature  of  the 
load,  predetermines  the  degree  of  regulation  which  must  be  ob- 
tained under  both  accidental  and  working  conditions,  but  it  is 
quite  evident  that  the  tendency  in  modern  plants  is  in  the  direc- 
tion of  apparatus  which  requires  closer  speed  regulation  and  more 
facility  in  handling  the  speed  than  heretofore. 

It  is  quite  possible  to  obtain  on  the  market  water-wheel  gov- 

203 


204  APPENDIX. 

ernors  which  will — provided  the  design  of  plant  is  good — give 
quite  as  good  a  speed  regulation  as  could  be  obtained  if  the  plant 
were  driven  by  first-class  steam-engines. 

There  is  more  than  one  water-driven  electric  plant  in  this 
country  where  auxiliary  steam-plants  are  used  in  which  the  speed 
is  fully  as  constant  while  the  load  is  carried  by  the  water-wheels 
as  while  it  is  carried  by  the  steam-plant.  The  plants  of  the  Derby 
Gas  Co.,  the  Pawtucket  Electric  Co.,  and  the  Woonsocket  Electric 
Co.  may  be  referred  to  as  examples  illustrating  the  above  fact. 

The  largest  accidental  load  variation  which  can  occur  is  evi- 
dently an  instantaneous  change  amounting  to  the  full  capacity 
of  the  water-wheels.  The  working-load  variations  may  be  any- 
thing less  than  this. 

The  writer  has  found,  in  a  practice  amounting  to  something 
over  90,000  H.P.  of  water-wheels  in  the  last  four  years,  that  with 
good  water-wheels  properly  set  and  rigged,  and  controlled  by 
governors  of  suitable  design,  the  speed  may  be  held  within  5  or 
6%  of  normal  upon  circuit-breakers  opening  under  full  load,  and 
that  the  speed  may  be  brought  back  to  normal  in  from  five  to 
fifteen  seconds,  depending  upon  the  amount  of  kinetic  energy  in 
the  rotative  parts  and  moving  water-column.  With  incandescent 
loads  of  the  ordinary  type,  a  recording  tachometer  will  show  a 
practically  straight  line.  With  ordinary  electric-railway  loads 
speed  variations  of  about  3%  as  a  maximum  may  be  expected. 
These  figures  are  not  intended  to  be  of  universal  application,  but 
are  for  simply  showing  the  present  state  of  the  art.  It  should  here 
be  added  that  governors  can  be  obtained  which  will  permit  any 
number  of  independent  water-wheel  units  driving  electrical  units 
connected  in  parallel  to  be  operated  with  perfect  convenience  and 
safety.  It  should  also  be  noted  that  in  the  case  of  alternating 
units  it  is  perfectly  easy  to  get  them  at  speed  and  in  step  for  multiple 
connection  without  undue  delay,  and  without  any  hand  regulation. 

These  desirable  ends  cannot,  however,  be  obtained  to  their 
fullest  extent  if  the  general  design  of  the  hydraulic  portion  of 
the  plant  is  bad.  We  will  now  consider  those  things,  aside  from 
the  governor  itself,  which  tend  to  make  the  regulation  good  or 
bad. 

As  a  preliminary  thought  let  us  consider  for  a  moment  that 


APPENDIX.  205 

the  problem  is  quite  different  from  steam-engine  governing,  which 
naturally  comes  to  the  mind  hi  this  connection,  for  the  reason  that 
water  is  heavy,  practically  non-compressible  or  non-expansive, 
and  must  be  transmitted  to  the  water-wheel  in  large  volume  and 
at  low  velocity;  while  steam  is  light,  highly  compressible  and 
expansive,  and  may  be  transmitted  to  the  engine  in  small  volume 
and  at  high  velocity.  From  this  it  follows  that  the  engine-valves 
are  small,  light,  and  may  be  perfectly  balanced,  while  water-wheel 
gates  are  necessarily  large,  heavy,  and  are  frequently — although 
often  unnecessarily — out  of  balance.  The  inertia  of  the  steam 
may  be  always  neglected;  the  inertia  of  the  water  must  be  always 
considered. 

The  problem  governing  a  water-wheel,  then,  involves  moving 
large  volumes  of  a  heavy  practically  incompressible  fluid  acted 
on  by  the  force  of  gravity  alone,  and  of  moving  ponderous  gates; 
and  this  must  be  done  with  absolute  precision  and  great  prompt- 
ness. Also  adequate  provision  must  be  made  for  the  momentum 
and  inertia  of  the  moving  water  and  mechanical  parts. 

To  put  our  minds  in  a  proper  attitude  to  approach  this  subject 
let  us  refresh  our  memories  in  regard  to  some  of  the  relations  of 
force,  mass,  velocity,  and  time. 

We  have  here  a  mass  free  to  move.  Its  property  of  inertia 
prevents  its  moving  until  some  force  is  applied  to  it.  When, 
however,  I  apply  for  a  moment  the  force  of  my  hand  it  begins 
to  move,  and  when  I  stop  pushing  it,  it  continues  to  move  with 
a  fixed  velocity  until  I  apply  to  it  the  same  amount  of  force  I 
used  to  put  it  in  motion  which  brings  it  to  a  rest,  and  it  cannot 
move  again  until  a  new  force  is  applied  to  it. 

I  have  here  a  pendulum  beating  seconds,  and  here  (Fig.  1) 
are  two  masses  consisting  of  pairs  of  balanced  weights  suspended 
by  fine  wires  over  pulleys  which  have  as  little  friction  as  possible- 
One  of  these  masses  is  twice  as  great  as  the  other.  If  we  apply 
to  them  equal  forces  in  the  shape  of  small  additional  weights, 
we  will  find  that  at  the  end  of  1  second  the  smaller  mass  has  acquired 
twice  the  velocity  of  the  larger  mass;  or,  in  other  words,  where 
forces  are  equal  the  rates  of  acceleration  are  inversely  proportional 
to  the  masses. 

But  now  I  have  here  two  equal  masses  (Fig.  2) ,  and  if  we  apply 


206 


APPENDIX. 


to  them  two  forces — one  twice  as  great  as  the  other, — we  will 
observe  that  at  the  end  of  1  second  the  velocity  of  the  mass  acted 
upon  by  the  larger  force  is  twice  as  great  as  that  of  the  mass  acted 
upon  by  the  smaller  force;  or,  in  other  words,  where  masses  are 
equal  the  velocities  are  proportional  to  the  forces. 


Now,  I  have  here  two  masses  (Fig.  3),  one  twice  as  great  as 
the  other,  and  if  we  apply  to  the  larger  mass  a  force  twice  as  great 
as  that  which  we  apply  to  the  smaller  mass,  we  will  observe  that 
at  the  end  of  1  second  their  velocities  are  the  same;  or,  in  other 
words,  for  equal  velocities  the  forces  must  be  proportional  to  the 


masses. 


APPENDIX.  207 

Or,  to  generalize:  velocities  are  inversely  proportional  to 
masses,  and  directly  proportional  to  forces. 

Or,  by  assuming  the  unit  of  force  as  that  force  which  will,  in  unit 
time,  give  unit  mass  unit  velocity,  we  may  formularize  the  phe- 
nomena we  have  observed  by  writing 

Force  X  Time  =  Mass  X  Velocity,      ....(!} 
from  which  we  may  get  by  transposition 
Force=MassXVelocity 


Time 


Force 


,,          Force  X  Time 

Mass=     „  .  —  r-  -  .......     .     .     (4) 

Velocit 


T7  ,     .          For  ceX  Time 

Velocity  =  -  ^  -  .......     (5) 

*  \\c\r*c*  N        * 


The  product  of  "force"  into  "time"  is  called  "impulse,"  and 
the  product  of  "mass"  into  "velocity"  is  called  "momentum"; 
the  equation  teaches  us  that  an  "impulse"  is  equal  to  the  "momen- 
tum" which  it  produces. 

It  is  chiefly  with  the  practical  application  of  the  laws  we  have 
just  enunciated  that  we  have  to  do  in  regulating  the  speed  of 
water-wheels. 

Let  us  examine  still  further  into  the  matter.  We  know  that 
if  we  let  any  weight  fall  freely  under  the  force  of  gravity — or 
as  it  is  usually  written,  with  a  force  =g, — at  the  end  of  one  second 
it  will  have  acquired  a  velocity  of  approximately  32.2  ft.  per  second; 
or,  if  we  throw  any  weight  up  with  an  initial  velocity  of  32.2  ft. 
per  second,  the  force  of  gravity  will  stop  it  in  1  second. 

In  the  latter  case,  the  velocity  at  the  start =32.2,  and  the 
velocity  at  the  end  of  the  second  =0,  and  the  mean  or  average 
velocity  and  the  distance  it  will  travel  =  32. 2  -7-2  =  16.1  in  the  first 
second.  Therefore  the  work  in  foot-pounds  which  any  weight, 


208  APPENDIX. 

can  do  by  being  thrown  vertically  with  an  initial  velocity  of  32.2 
ft.  per  second  =  weight  x|-  ft. 

Please  note  that  in  above  case  the  initial  velocity  (V)  =g  or 
32.2,  and  that  V+g  =  l. 

If,  however,  we  have  thrown  the  weight  upward  with  an  initial 
velocity  twice  as  great  as  before,  i.e.,  64.4  ft.  per  second,  the  force 
of  gravity  would  stop  it  in  2  seconds;  but  the  mean  velocity  in 
this  case  is  64.4-^2  =  32.2,  which  is  twice  what  it  was  before,  and 
we  must  also  note  that  it  was  traveling  upward  twice  as  long  as 
before;  hence,  by  doubling  both  the  velocity  and  the  length  of 
time,  it  will  ascend  four  times  as  far.  Thus,  by  doubling  its  V+g, 
which  in  the  latter  case  =  2,  we  have  enabled  the  weight  to  do  four 
times  the  work.  Or,  we  may  truthfully  state  that  in  the  second 
case  the  work  equals  that  in  the  first  .case  multiplied  by  (V+g)2; 
or,  formulating  it, 


q      iV\2 
Work  in  foot-pounds  =  Weight  X  |-  X  ( —  J  , 


(6) 


a      V2 
Work  in  foot-pounds  =  Weight  X  |  X  -$ ,      .     .     .     (7) 

V2 

Work  in  foot-pounds  =  Weight  X^r-;        ....     (8) 


or  we  may  more  conveniently  write  it 

;        ....     (9) 


which  is  the  form  in  which  we  will  have  occasion  to  most  often 
use  it. 

As  this  is  a  universal  law  applicable  to  any  force  and  any  velocity, 
it  is  applicable  to  water  falling  under  the  influence  of  gravity. 

To  fix  it  in  our  minds  let  us  apply  it  numerically  to  the  masses 
with  which  we  have  been  experimenting.  Start  with  the  masses 
as  shown  in  Fig.  2. 

Let  the  masses  M  and  MI  be  equal,  and  let  them  each  be  numer- 


APPENDIX.  209 

ically  equal  to  1.     Let  F=2  and  Fi  =  4.    Let  their  time  of  action 
T=  1  second,  then  their  velocities  at  the  end  of  the  time  T  will  be 


FT  _2X1 

=~"  ~ 


_. 


Now  at  the  end  of  the  time  T  stop  the  action  of  the  forces  F 
and  FI  and  apply  to  the  masses  M  and  MI  in  an  opposite  direction 
a  new  force  F2=2.  This  new  force  will  stop  the  masses  in  the 
following  lengths  of  time: 

MXF1X2_ 

2~  !Bl' 

lX4 

T~ 

But  the  space  /Si  and  82  through  which  they  will  travel  before 
they  stop  will  be 

o      VTt     2X1 
^1  =  ^-:   —  Bl' 
F2T2    4X2 


or  the  masses  are  as  ................................  1:1 

and  the  forces  applied  to  them  are  as  .................  2:4 

for  lengths  of  time  which  are  as.  ....  .................  1:1 

which  give  them  velocities  which  are  as  ...............  2:4 

and  cause  them  to  travel  through  spaces  which  are,  during 

time  T7,  as  .......................................  1:2 

consequently  doing  work  on  them  which  are  as 


2:8 


They  can  then  oppose  equal  forces  through  spaces  which 
are  as  ..........................  -  .................   1:4 

during  lengths  of  time  which  are  as  ................   1:2 


210 


APPENDIX. 


consequently  doing  amounts  of  work  which  are  as 

FS    and    FSi     or     (2X1):  (2X4)     or 2:8 

In  the  above  case  the  masses  M  and  MI  should  consist  of 
weights  of  32.2  Ibs.;  that  is,  the  weight  at  each  end  of  the  wire 
should  be  16.1.  The  force  F=2  Ibs.,  Fi  =  4  Ibs.,  F2  =  2  Ibs.  A 
pendulum  39.1  inches  long  from  center  of  weight  to  point  of  sup- 
port will  beat  near  enough  seconds  for  ordinary  experimental 
purposes.  A  few  experiments  carefully  carried  out  with  the 
apparatus  shown  in  Figs.  1,  2,  and  3  will  teach  one  more  about  the 
relations  of  mass,  force,  time,  and  velocity  than  can  readily  be 
learned  in  any  other  way. 

We  are  now  prepared  to  see  the  application  of  the  laws,  and 
the  formulae  we  have  written,  directly  to  one  of  the  most  impor- 
tant details  connected  with  the  installation  of  water-wheels.  This 
can  be  best  shown  by  an  example. 

We  have  here  two  water-wheels  (Fig.  4)  operating  under  the 
same  head,  which  we  will  assume  to  be  nine  (9)  ft.  You  will 


observe  that  although  the  head  is  the  same  in  both  cases,  one 
wheel — which  we  will  designate  No.  1 — is  set  in  an  open  flume 
of  ample  size;  while  the  other  wheel — which  we  will  designate 
as  No.  2 — is  in  a  closed  flume  connected  to  open  water  by  a  long 
closed  pipe  which  is  nearly  horizontal.  The  behavior  of  these 
two  wheels  when  operating  under  variable  load  is  entirely  different. 
Let  us  assume,  for  the  purposes  of  argument,  that  the  efficiency 
of  the  wheel  is  the  same  at  all  stages  of  gate,  and  that  the  amount 
of  water  which  passes  through  the  wheel  is  proportional  to  the 
gate-opening,  and  that  the  -power  of  the  wheel  is  proportional 
to  the  amount  of  water  which  passes  through  it  under  constant 


APPENDIX.  211 

pressure.  Now,  if  the  wheel  is  operating  at  full  gate  and  half 
the  load  is  suddenly  thrown  off,  and  the  suitably  designed  gov- 
ernor attached  to  the  wheel  promptly  shuts  the  gates  so  that 
only  one  half  as  much  water  can  pass  as  when  the  wheel  was  at 
full  gate,  it  is  evident  that  the  speed  will  remain  comparatively 
constant. 

Let  us  see  if  this  will  be  the  case  with  wheel  No.  2.  If  it  is 
operating  at  full  load,  and  half  the  load  is  instantly  thrown  off,, 
and  the  governor  promptly  shuts  the  gates  so  that  only  half  as 
much  water  can  pass,  it  is  evident  that  the  velocity  of  the  water 
in  the  closed  pipe  must  be  reduced  jone  half. 

If  we  assume  that  the  water  in  the  pipe  weighs  1,000,000  lbs.; 
and  has  a  velocity  at  full  head  of  4  ft.  per  second,  its  energy  (see 
formula  9)  =1,000,000 -=-32.2 X42 --2  =248,440  ft.-lbs.,  and  if  the 
water  velocity  at  half  load  is  2  ft.  per  second,  then  its  energy 
=  1,000,000-5- 32.2x22-v-2  =  62,110  ft.-lbs.,  and  the  difference  be- 
tween these  two  amounts  of  energy,  248,440-62,110=186,330- 
ft.-lbs.,  must  be  expended  upon  the  water-wheel  before  the  water 
velocity  is  reduced  to  2  ft.  per  second. 

If  it  were  expended  in  one  second  it  would  =  186,330-7-550  H.P., 
but  this  is  a  little  quicker  than  we  would  expect  to  do  in  prac- 
tice. Suppose  we  slow  up  the  water-column  in  two  seconds, 
then  the  energy  expended  =186,330 -7-550X2  =169  H.P.  for  two- 
seconds.  The  above  value  of  H.P.  would  not  hold  strictly  true 
unless  the  rate  at  which  the  gate  closed  was  proportional  to  the 
rate  at  which  the  water-column  slowed  up;  but  the  total  foot-pounds 
expended  on  the  wheel  would  be  as  above  stated.  To  find  the 
exact  value  of  H.P.  at  any  instant  of  time  would  require  a  more 
elaborate  mathematical  treatment  of  the  problem  than  the  time 
now  at  our  disposal  permits;  but  the  significant  fact  to  which 
I  wish  to  call  your  attention  is  that  this  work  done  upon  the  water- 
wheel  in  slowing  up  the  water-column  is  entirely  independent 
of,  and  in  excess  of,  the  work  which  is  expended  upon  the  water- 
wheel  when  it  is  working  normally  at  half  gate,  with  the  water- 
column  moving  at  a  fixed  velocity. 

It  is  evident  that  the  above  amount  of  work  done  upon  the 
wheel  while  the  water-column  is  slowing  up  would  tend  to  make 
the  speed  of  the  water-wheel  run  high  if  the  governor  only  half 


212  APPENDIX. 

closed  the  gates.  In  fact,  the  governor  would  have  to  set  the 
gates  much  nearer  closed  than  one  half;  or,  to  speak  more  accu- 
rately, the  governor  would,  at  each  instant  of  time,  have  to  hold 
the  gates  at  such  a  position  that  the  power  developed  by  the 
wheel,  due  to  the  working-head  plus  the  instantaneous  value  of 
power  being  developed  by  the  slowing  water-column,  equaled 
the  load  upon  the  wheel. 

This  might  be  found  to  be  quite  unfeasible,  for  the  pressure 
developed  on  the  closed  pipe  and  wheel-case  might  be  dangerous, 
or  the  gate  might  be  too  ponderous  or  too  badly  rigged  to  per- 
mit of  the  requisite  promptness  of  motion. 

The  maximum  pressure  which  would  be  developed  at  any 
instant  of  time  at  the  water-wheel  would  be  an  impossible  thing 
to  calculate  without  knowing  a  great  deal  more  about  the  venting 
areas  and  time-ratio  of  closing  them  than  can  ordinarily  be  found 
out  in  practice.  All  that  can  be  predetermined  is  what  may  be 
called,  for  want  of  a  better  term,  the  time-average  pressure.  This 
can  easily  be  determined  as  follows: 
Let  P=the  time-average  pressure; 

L=the  length  of  the  closed  flume  in  feet; 
F=the  water  velocity  in  feet  per  second; 
,  T=the  time  in  seconds  in  which  the   water  velocity  is 

arrested; 

K=  the  area  of  a  square  inch  expressed  in  square  feet  = 
.00694.     Then 

XX62.4XLXF 
~~ 


It  will  be  observed  that 

~irf  \*  fity  A 

—  ^-^-  =:  .01324  is  a  constant,  call  this 

&a»a 

and  the  formula  becomes 


,  - 


APPENDIX.  2i3 

Applying  this  to  the  flume  we  have  been  discussing,  in  which 

L=300, 

7=2, 

!T=2, 

we  have 

p     .01324  X  300  X2_0fV7 
r=          —  ^  —         —  o.y/. 

As  a  water-column  1  ft.  high  exerts  a  pressure  of  .43  Ib.  per 
square  inch,  it  follows  that  a  pressure  of  3.97  Ibs.  per  square  inch 
represents  a  head  of  3.97  -=-.43  =  9.2  ft.  In  other  words,  if  the 
pressure  on  the  wheel  could  have  been  kept  constant  all  the  time 
the  water-column  was  slowing  up  from  4  ft.  per  second  to  2  ft. 
per  second,  the  wheel  would  have  been  working  under  9  +  9.2 
=  18.2  ft.  of  head,  instead  of  under  9  ft.  of  head  as  it  should  have 
been. 

From  experience  we  know  that  it  is  impossible  to  close  the 
water-wheel  gates  at  such  a  rate  as  to  keep  the  pressure  constant, 
-and  as  a  matter  of  fact,  during  some  portion  of  the  two  seconds 
the  water-pressure  would  have  been  greatly  in  excess  of  3.97  Ibs. 
per  square  inch  above  normal,  with  a  correspondingly  large  dis- 
turbance of  the  speed. 

We  may  note  a  curious  fact  in  this  connection.  With  a  water- 
wheel  set  like  No.  2  in  Fig.  4,  working  at  nearly  full  gate,  and 
if  under  these  conditions  a  large  portion  of  the  load  is  instantly 
thrown  off  and  the  governor  is  of  unsuitable  design  and  does  not 
compensate  for  the  kinetic  energy  of  the  slowing  water-column, 
"it  may  be  found  by  experiment  that  the  speed  will  run  higher 
than  though  there  were  no  governor  at  all.  This  is  for  the  reason 
that  for  an  interval  of  time  the  wheel  is  working  under  light  load 
and  a  greatly  increased  head,  and  there  is,  consequently,  a  greatly 
increased  speed;  or,  we  may  say  that  the  amount  of  energy  applied 
to  the  wheel  under  the  increased  pressure,  even  though  the  gate 
areas  have  been  somewhat  reduced  by  the  governor,  is  greater 
than  would  have  been  the  case  had  the  gates  not  been  moved 
at  all. 

The  first  remedy  which  suggests  itself  is  to  place  large  relief- 


214  APPENDIX. 

valves  near  the  wheel-case,  so  that  they  will  open  and  let  the 
water  escape  if  the  water  much  exceeds  the  static  head.  This 
would  help  matters  somewhat  upon  load  suddenly  going  off,  but 
would  it  help  matters  upon  load  suddenly  going  on?  Let  us 
examine  this  matter. 

Suppose  the  wheel  is  working  at  half  load  with  the  water- 
column  moving  at  a  rate  of  2  ft.  per  second,  and  the  whole  load 
is  instantly  thrown  on  the  wheel.  The  governor  will  promptly 
open  the  gate  wide,  but  the  water-wheel  cannot  develop  its  whole 
power  until  the  water-column  has  attained  a  velocity  of  4  ft.  per 
second.  To  gain  this  extra  2  ft.  per  second  the  water-column 
must  have  expended  upon  it  the  same  amount  of  work  which  it 
expended  in  losing  its  2  ft.  per  second,  namely,  186,330  ft.-lbs., 
and  this  must  be  deducted  from  the  work  the  wheel  will  do  nor- 
mally at  full  gate;  so  that  the  instantaneous  value  of  power 
developed  by  the  wheel  while  the  water-column  is  gaining  velocity 
would  equal  the  normal  power  of  the  wheel  at  full  gate  minus 
the  instantaneous  value  of  power  being  expended  upon  the  water- 
column  in  getting  up  to  speed. 

It  is  evident  that  the  speed  of  the  water-wheel  would  fall  con- 
siderably below  normal  and  there  would  be  absolutely  no  remedy 
for  it  in  the  present  state  of  the  art.  I  say  this  advisedly  and 
have  not  forgotten  the  question  of  fly-wheels,  which  is  undoubt- 
edly in  all  of  your  minds  at  the  present  moment. 

Let  us  now  consider  how  long  it  will  take  the  water-column  to 
get  up  to  speed.  First  let  us  look  again  at  wheel  No.  1  for  a 
moment.  We  know  that  the  velocity  of  water  falling  without 
friction  may  be  expressed  by  the  formula. 

V=V2gXH, (12) 

where  V= velocity  in  feet  per  second, 
2  =  32.2, 
H= head  in  feet. 

Taking  2g  outside  of  the  square-root  sign,  we  have 

7= 8.025V '~H (13) 


APPENDIX.  215 

This  is  the  velocity  with  which  water  should  enter  the  water- 
wheel. 

For  purposes  of  simplicity  I  have  in  this  paper  ignored  the 
corrections  which  should  be  made  for  water  friction  on  surfaces 
and  in  orifices,  as  they  do  not  alter  to  any  large  extent  the  stub- 
born facts  we  are  considering.  Such  corrections  are  beyond  the 
scope  of  this  paper. 

Applying  formula  No.  13  to  wheel  No.  1  and  assuming  that 
the  water  enters  the  wheel  without  friction,  we  have 

Velocity  of  water  entering )  /-          £ 

^     A  **  t.     j    1  =  8.025V  9=24  ft.  per  second, 
wheel  under  9  ft.  head    ) 

Now,  as  the  time  required  for  a  falling  body  to  acquire  a  given 

y 
velocity  = — ,  we  find  in  the  case  of  wheel  No.  1 

Time  in  seconds  for  water  to  ac-  ^       v 
quire   spouting  velocity   into  >  =  —  =  ^-  =  .7  second 
wheel  under  9  ft.  head  J 

Thus,  if  the  gates  being  closed  were  instantly  opened,  the 
water  would  be  doing  its  full  amount  of  work  on  the  wheel  in 
seven  tenths  of  a  second. — To  make  the  above  absolutely  true 
it  would  be  necessary  to  assume  that  the  water  would  enter  the 
wheel  with  equal  freedom  at  all  si  ages  of  gate,  which  is  not  the 
case,  but  it  is  sufficiently  near  the  truth  for  our  present  argu- 
ment. We  are  also  ignoring  what  is  known  as  the  velocity  of 
approach  for  reasons  previously  stated. 

To  make  sure  that  our  figures  are  right  let  us  calculate  the 
value  of  V  from  our  fundamental  equation  (No.  5), 

FT 
7=_ 

M' 

Assume  a  vertical  water-column  of  1  sq.  ft.  area  and  9  ft.  high. 
Its  weight  is  62.4X9  =  560.7:  this  =  F.  Then 

561.6X.7 
561.6     ~^>b' 
32.2 


216  APPENDIX. 

which  is  a  close  approximation  to  the  value  of  V=24  previously 
found,  the  slight  discrepancy  being  due  to  the  fact  that  62.4  is- 
not  the  exact  weight  of  a  cubic  foot  of  water,  and  32.2  is  not  the 
exact  value  of  g.  It  might  also  be  added  that  the  square  root  of 
2g= 8.025,  which  is  usually  given  in  books  on  hydraulics,  and  which 
was  previously  given  in  formula  No.  13,  is  a  trifle  too  large,  and  a 
closer  approximation  to  truth  will  be  obtained  by  calling  it  8.02. 
By  using  better  values  we  can  bring  out  F=23.8. 

Now,  in  case  of  wheel  No.  2  the  water  will  behave  in  an  entirely 
different  manner.  We  know  that^the  spouting  velocity  at  wheel 
No.  2  is  the  same  as  at  wheel  No.  1  minus  the  friction  of  the  pipe. 
Unfortunately,  we  are  concerned  not  only  with  the  spouting 
velocity  at  wheel  No.  2,  but  with  the  length  of  time  it  will  take  to 
attain  spouting  velocity  at  wheel  No.  2.  The  water,  instead  of 
falling  vertically  as  in  wheel  No.  1,  runs  down  an  almost  horizontal 
inclined  plane.  A  large  part  of  the  force  of  gravity  is  applied 
perpendicularly  to  the  inclined  plane  and  the  small  remainder  is- 
applied  to  shove  the  water  down  the  inclined  plane.  A  diagram 
will  make  this  clear. 

Let  A  in  Fig.  5  =  the  head  in  feet  from  open  water  above  the 
entrance  to  the  flume  to  tail  water  level. 

Let  B  =  the  horizontal  distance  in  feet  from  entrance  to  flume 
to  draft-tube  at  tail  water  level. 

Then  C=the  hydraulic  slope. 

Project  Ci  =  A  =  the  hydrostatic  head. 

Draw  D  perpendicular  to  C. 

Complete  the  parallelogram. 

Then  the  force  C\  (which  we  must  remember  is  the  hydrostatic 
head)  is  equal  to  the  forces  A\  and  D,  of  which  the  latter  is  wholly 
sustained  by  the  reaction  of  the  plane  C\,  while  A  is  wholly  effective 
in  accelerating  the  motion  of  water  down  the  slope  C.  We  evidently 
wish  to  know  the  value  of  A  i  in  terms  of  the  triangle  ABC,  which 
is  similar  to  the  triangle  AiBiC\. 

We  know  that  Ai  =  Cisineai.  Then  as  Ci  =  A  and  ai  =  a, 
it  follows  that  Ai  =  Asmea.  Let  us  designate  the  value  of  AI 
so  found  as  /. 

We  have  seen  (Fig.  3)  that  the  time  to  give  equal  masses  equal 
velocities  is  inversely  proportional  to  the  forces. 


APPENDIX. 


217 


Calling  T  the  time  to  acquire  spouting  velocity  down  A,  and 
the  time  to  acquire  spouting  velocity  down  C,  we  may  write 


T1:T  =  f:A 


from  which  we  get 


(14) 


(15) 


Let  us  apply  this  equation  (15)  to  the  case  of  wheel  No.  2  in 
Fig.  4. 

The  head          A  =  9  ft. 
Assume  B  =  298.7  ft. 

Then 


C=V92X298.72  =  300  feet, 


then 


. 

Ai  =  A  sine  a=9X.03=.27=/, 
A  =  9, 
T=.7,  previously  found; 


TA     .7X9 

i-—  =-^-23.3 


seconds  required  for  water  to  acquire  spouting  velocity  down 
spouting  slope  C. 

It  may  be  noted  that 


TA 


may  be  written 


which  by  cancellation  becomes 


which  is  its  simplest  form,  and  in  which  it  should  be  used. 


CIVIL  ENGINEERING 
U.  of  C. 


.218 


APPENDIX. 


To  make  the  above  reasoning  plainer,  I  have  plotted  (see  Fig. 
6)  lines  showing  the  time  necessary  for  water  to  acquire  spouting 
velocities  into  the  two  water-wheels  in  Fig.  4.  Line  0-1  shows 
the  time  for  water  to  acquire  any  velocity  up  to  spouting  velocity 
into  wheel  No.  1 ;  line  0-2  shows  the  time  for  water  to  acquire  any 
velocity  up  to  spouting  velocity  into  wheel  No.  2. 

It  naturally  occurs  to  one  hi  this  connection  that  the  water 
never  has  occasion  to  acquh-3  spouting  velocity  in  the  flume  of 
wheel  No.  2;  in  fact,  we  assumed  that  the  maximum  water  velocity 
in  this  flume  was  only  4  ft.  per  second,  which  is  only  one  sixth  of 


Fie.  6. 


TIM*     In 


spouting  velocity.  It  can  be  shown  mathematically,  and  experi- 
ment proves,  that  this  does  not  interfere  with  the  line  of  reasoning 
we  have  been  following.  If,  instead  of  the  end  of  the  flume 
being  wide  open,  it  were  five  sixths  closed,  the  remaining  sixth 
being  an  orifice  (the  venting  areas  of  the  water-wheel)  capable  of 
being  varied  at  will,  it  would  simply  mean  that  in  the  flume  the 
value  of  #=32.2  would  be  considerably  reduced.  This  new  value 
we  should  calculate  and  call  it  G.  We  could  then  substitute  it  for 
Ihe  value  of  g  we  have  been  using  in  our  calculations,  and  the  ratio 
of  velocity  and  time  in  the  open  flume  of  wheel  No.  1  and  in  the 
closed  flume  of  wheel  No.  2  would  be  found  to  be  the  same  that 
we  have  already  ascertained. 

But  it  may  be  argued  that  we  are  concerned  with  the  force 
which  the  water  will  apply  to  wheels  No.  1  and  No.  2  while  the 


APPENDIX.  219 

water  is  getting  up  to  spouting  velocity,  and  not  with  the  velocity 
of  the  water  itself.  Let  us  see  at  what  rate  the  water  will  develop 
its  full  amount  of  energy  on  the  two  wheels  we  have  been  con- 
sidering. 

The  theoretical  amount  of  energy  which  flowing  water  can  apply 
to  an  obstacle,  advantageously  placed  in  its  path,  may  be  expressed 
as  follows  : 


(18) 


where  P^the  theoretical  energy  developed, 

F=  the  force  of  impulse  and  also  of  reaction, 
W=  weight  of  water  flowing  per  second, 
w=  weight  of  1  cu.  ft.  of  water, 
a  =  cross-sect  ion  of  the  stream  in  square  feet. 

It  will  be  noted  that  if  we  assume  a=  1,  we  may  regard 

—  =  3.9 

as  a  constant,  which,  multiplied  by  the  square  of  the  velocity  of 
flow  in  feet  per  second,  will  give  the  theoretical  force  which  the 
water  will  develop.  I  have  calculated  the  force  developed  at 
wheel  No.  1  and  No.  2,  as  shown  in  Fig.  4,  for  each  tenth  of  a 
second,  beginning  with  the  water  at  a  rest  in  both  cases  and  ending 
with  spouting  velocity,  and  have  plotted  the  values  in  Fig.  7. 
Curve  0-1  shows  the  rate  at  which  water  standing  at  a  rest  develops 
its  full  energy  on  wheel  No.  1  ;  curve  0-2  shows  the  rate  at  which 
water  standing  at  a  rest  develops  its  full  energy  on  wheel  No.  2. 
You  will  note  in  the  case  of  wheel  No.  1  how  very  promptly  the 
energy  gets  to  its  maximum  value,  and  in  the  case  of  wheel  No  2 
how  the  energy  lags  for  a  considerable  time  before  it  arrives  at 
anything  like  its  maximum  value. 

I  wish  to  emphasize  this  line  of  reasoning,  because  it  is  perhaps 
the  most  important  thing  to  be  considered  in  setting  water-wheels 
where  speed  regulation  is  a  desideratum.  We  can,  in  an  imperfect 
way,  provide  for  the  expenditure  of  the  energy  necessary  to  slow 
up  a  water-column,  but  there  is  no  way  to  make  a  water-column, 


220 


APPENDIX. 


while  gaining  velocity,  do  the  work  it  is  capable  of  when  it  has 
arrived  at  full  velocity. 

The  important  fact  to  which  I  want  to  especially  call  your 
attention  is  that  the  difficulty  is  measured  not  only  by  the  length 
of  the  closed  flume,  but  is  inversely  proportional  to  the  sine  of  the 
angle  of  hydraulic  slope.  When  the  sine  becomes  1;  that  is, 
when  the  angle  is  90°, — or,  in  other  words,  when  the  closed  flume 


L.  J 

1 


T.I  HE  IN  SEC  ONES. 


is  vertical, — then  the  difficulties  due  to  the  fact  that  water  moves 
slowly  under  the  influence  of  gravity  have  reached  their  mini- 
mum and  the  speed  regulation  will  be  the  best  obtainable  As 
the  sine  of  the  angle  of  hydraulic  slope  grows  less,  then  the  obtain- 
able regulation  grows  worse. 

There  is  one  way  in  which  the  difficulties  attendant  upon  a 
small  angle  of  hydraulic  slope  may  be  in  a  measure  compensated 
for,  and  that  is  by  means  of  a  stand-pipe. 

In  an  electric  plant  it  is  not  usually  of  such  importance  that 


APPENDIX.  221 

a  load  change  amounting  to  the  full  capacity  of  the  wheels  be 
followed  by  a  small  speed  variation,  as  that  the  comparatively 
large  loads  which  go  off  and  on  for  short  intervals  of  time  shall 
not  disturb  the  speed  to  any  great  extent.  Here  is  where  the 
stand-pipe  is  of  value.  If  a  portion  of  the  load  goes  off  instantly 
and  the  correctly  designed  governor  promptly  closes  the  gates  to 
the  correct  position,  the  excess  of  water  will  flow  out  over  the 
top  of  the  stand-pipe  and  the  water  velocity  in  the  flume  will 
not  be  arrested  so  promptly  as  though  there  were  no  stand-pipe; 
neither  will  the  pressure  at  the  wheel  be  much  increased.  To 
obtain'  these  results,  the  stand-pipe  should  be  only  a  very  little 
higher  than  the  water  level  in  the  pond.  It  should  be  located 
as  near  the  wheels  as  possible,  and  its  top  should  be  turned  over 
so  that  the  escaping  water  can  be  led  to  some  convenient  point 
of  discharge. 

If,  after  a  load  has  gone  off  instantly,  it  comes  on  again  in  a 
short  interval  of  time,  it  finds  the  water  velocity  in  the  flume 
but  little  diminished,  and  also  the  vertical  water-column  in  the 
stand-pipe  is  ready  to  apply  its  energy  to  the  water-wheel  in  the 
most  advantageous  manner.  To  make  the  last  factor  of  much 
practical  use,  the  cross-section  of  the  stand-pipe  must  be  suffi- 
ciently large  to  prevent  the  level  of  the  enclosed  water-column 
from  falling  much  while  the  water  in  the  closed  flume  is  gaining 
its  lost  velocity.  As  a  general  statement,  the  larger  the  diameter 
of  the  stand-pipe  and  the  less  its  height  above  the  hydrostatic 
level,  the  better  will  be  the  speed  regulation.  There  has  not,  as 
yet,  been  sufficient  practical  experience  with  stand-pipes  to  for- 
mulate rules  which  will  solve  the  least  diameter  which  will  result 
in  any  desired  degree  of  speed  regulation. 

In  the  writer's  experience,  it  has  been  found  that  the  use  of  a 
stand-pipe  of  ample  proportions  will  render  a  plant  governable 
within  very  close  limits  under  ordinary  operative  conditions 
which  had  proved  to  be  utterly  ungovernable  before  the  stand- 
pipe  was  installed. 

From  what  has  been  said  above  it  will  be  seen  that  a  stand- 
pipe  is  chiefly  of  use  in  aiding  a  good  governor  to  maintain  a 
comparatively  constant  speed  under  those  frequently  recurring 
load  changes  which  obtain  in  electric  plants, — especially  in  electric 


222 


APPENDIX. 


railway  and  power  plants.  It  also  gives  perfect  protection  against 
dangerous  water-pressures  being  developed  when  circuit-breakers 
open,  or  when,  for  accidental  reasons,  it  is  necessary  to  shut  down 
the  water-wheels  instantly. 

A  stand-pipe  will  not — unless  of  very  large  diameter — enable 
a  good  governor  to  maintain  a  good  degree  of  speed  regulation 
if  the  load  be  increased  from  friction  load  to  full  load  instantly, 
where  the  angle  of  hydraulic  slope  is  small,  unless  such  increase 
of  load  takes  place  before  the  water  in  the  enclosed  flume  has 
lost  much  of  its  velocity. 

The  writer  had  intended  to  refrain  entirely  from  submitting 
designs  showing  the  proper  setting  of  water-wheels,  for  the  reason 
that  such  a  large  number  of  typical  plans  would  be  required  to 
.cover  all  probable  cases  that  it  would  be  hopeless  to  treat  the  sub- 
ject properly  without  extending  this  paper  beyond  proper  limits. 
He  cannot,  however,  resist  the  temptation  to  introduce  at  this  point 
one  design  (shown  in  Fig.  8)  which  has  proved  to  be  singularly 
adapted  to  the  demands  of  water-power-driven  electric  plants. 


FIG.  a 


It  will  be  noted  that  the  wheels  are  arranged  for  direct  connec- 
tion. The  angle  of  hydraulic  slope  is  practically  90°,  giving  the 
best  possible  conditions  for  speed  regulation.  The  governor  may 
be  placed  directly  outside  the  flume-head  and  connected  to  the 
gates  in  the  simplest  possible  manner.  The  speed  variations  of 
the  main  shaft  may  be  transmitted  to  the  governor  by  one  belt. 
The  requisite  R.P.M.  may  be  obtained  by  varying  the  diameter 


APPENDIX.  223 

and  number  of  wheels.  The  number  or  size  of  wheels  on  the  one 
shaft  may  vary  from  one  to  as  many  as  can  be  handled  by  one 
governor,  or  as  may  be  required  by  the  capacity  of  the  electrical 
unit.  This  general  design  has  found  favor  in  a  number  of  the 
most  prominent  plants  in  this  country  as  well  as  in  Europe.  The 
regulation  is  invariably  good  if  a  suitable  governor  be  used. 

It  is  usually  the  case  that  part  of  the  head  utilized  in  modern 
plants  is  below  the  water-wheel  in  the  shape  of  a  draft-tube;  in 
fact,  where  horizontal  wheels  are  used,  it  is  practically  necessary 
to  have  them  a  number  of  feet  above  tailwater  level  for  con- 
venience of  connection  to  the  driven  machinery. 

The  same  general  rule  holds  good  in  regard  to  draft-tubes, 
which,  we  have  found,  applies  to  closed  flumes.  They  should  be 
as  short  and  as  nearly  vertical  as  "possible.  The  maximum  ver- 
tical length  of  a  draft-tube  is,  of  course,  limited  by  the  atmospheric 
pressure.  The  water  stands  in  the  draft-tube  for  the  same  rea- 
son that  mercury  stands  in  a  barometer.  The  specific  gravity 
of  mercury  is  13.6:  that  is,  it  is  13.6  times  as  heavy  as  water. 
Atmospheric  pressure  holds  mercury  up  in  the  barometer  tube,— 
let  us  say  30  ins.  or  2|  ft., — therefore  it  will  hold  water  up  in  the 
draft-tube  2.5X13.6  =  34  ft.;  that  is,  it  would  do  so  if  the  draft- 
tube  were  air-tight.  The  external  atmospheric  pressure  at 
the  top  of  such  a  draft-tube  would  be  14.7  Ibs.  per  square  inch. 
There  are  few  draft-tubes  that  would  stand  that  pressure  with- 
out leaking  air.  This  fact  is  well  recognized  by  hydraulic  engineers, 
and  it  is  rare  to  find  draft-tubes  25  ft.  high  from  tailwater  level 
to  water-wheel  centers.  If  the  water-wheel  is  likely  to  be  sub- 
jected to  large  load  variations,  it  is  very  desirable  that  the  draft- 
tube  should  have  a  much  less  vertical  height  for  the  following  rea- 
son: 

At  the  bottom  of  a  25-ft.  vertical  draft-tube  the  atmospheric 
pressure  is  forcing  the  water  up  with  a  pressure  of  14.7  Ibs.  per 
square  inch,  and  the  weight  of  the  water  is  pressing  down  with 
a  pressure  of  10.81  Ibs.  per  square  inch:  that  is.  the  difference 
between  the  air-pressure  and  the  weight  is  14.7—10.81  =  3.89  Ibs. 
per  square  inch.  Now,  if  the  water  velocity  in  the  draft-tube 
is  suddenly  arrested  by  shutting  the  water-wheel  gates,  the  kinetic 
energy  of  the  slowing  water-column  will  be  found  in  the  down- 


224  APPENDIX. 

ward  momentum  of  the  water.  This  may  easily  create  a  down- 
ward pressure  greater  than  3.89  Ibs.  per  square  inch,  in  which 
case  a  vacuum  would  be  formed  in  the  upper  part  of  the  draft- 
tube  and  the  column  of  water  would  sink  in  the  draft-tube  and 
immediately  after  would  rush  upward  again,  striking  the  bottom 
of  the  wheel  with  great  violence.  If  we  were  so  fortunate  as  to 
escape  an  accident  of  the  kind  above  described  we  should  find 
that  with  a  draft-tube  of  considerable  height  there  is  a  tendency 
for  air  to  leak  in,  and  this,  under  the  negative  pressure  of  the 
weight  of  the  water,  expands  into  a  partial  vacuum  so  that  the 
draft-tube  will  be  only  partly  filled  with  water,  and  as  the  posi- 
tion of  the  water-wheel  gates  varies  as  the  load  changes,  the  water- 
column  in  the  draft-tube  will  sway  up  and  down,  producing  the 
effect  of  a  pulsating  head  on  the  water-wheel.  This  is  very  detri- 
mental to  good  speed  regulation,  and  is  a  very  common  annoy- 
ance encountered  in  practice.  The  performance  of  such  a  draft- 
tube  may  be  easily  illustrated  by  holding  a  mercurial  barometer 
in  the  hand  and  slowly  moving  it  up  and  down. 

Air-chambers  on  flumes,  to  give  protection  against  water-ham- 
mer effects,  are  of  very  little  practical  use  unless  of  ample  size, 
even  if  they  are  full  of  air.  The  writer  examined  a  plant  so 
located  that  the  bursting  of  the  flume  would  have  destroyed  the 
whole  plant  and  ruined  an  investment  of  at  least  $100,000.  At 
the  lower  end  of  the  flume  was  a  large  air-chamber.  The  super- 
intendent in  charge  pointed  with  pride  to  it,  and  confidently 
expressed  the  belief  that  it  afforded  ample  protection  against  the 
dangerous  strains  on  the  flume  due  to  water-hammer.  Upon 
examining  the  air-chamber  it  was  found  to  be  entirely  filled  with 
water,  and  it  had  probably  been  in  that  condition  for  a  consider- 
able length  of  time.  Water  under  pressure  absorbs  air  with  great 
facility.  An  air-chamber  should  be  provided  with  an  air-pump 
which  may  be  readily  connected  to  some  convenient  source  of 
power,  and  with  a  gauge-glass  to  show  the  water  level.  When 
so  arranged,  and  if  of  ample  size,  it  affords  considerable  safety 
against  pressure  developed  when  load  goes  off  suddenly;  but  it 
is  of  no  practical  use  as  an  aid  to  the  governor  in  maintaining 
constant  speed. 

Aside  from  designing  the  water-column  along  the  lines  already 


APPENDIX.  225 

suggested,  so  that  the  water  may  gain  its  working  velocity  in  the 
least  possible  time  and  also  so  that  it  may  add  to  or  take  from  the 
water-wheel  the  least  amount  of  the  kinetic  energy  of  the  water, 
the  next  most  important  thing  is  the  design  of  the  water-wheel 
gates  and  the  method  of  connecting  them  to  the  governor. 

As  has  already  been  pointed  out,  the  gates  are  of  necessity  large 
and  heavy,  and  yet  they  must  be  moved  with  great  promptness 
and  precision.  The  writer  has  had  occasion  to  investigate  with 
more  or  less  accuracy  the  number  of  foot-pounds  necessary  to  open 
and  close  the  gates  of  several  hundred  water-wheels,  and  the  sur- 
prisingly large  variation  in  the  amount  of  energy  required  leads 
him  inevitably  to  the  conclusion  that  this  matter  has  not  received 
in  many  cases  the  careful  engineering  treatment  which  it  de- 
serves. 

Water-wheels  are  of  many  designs  and  sizes,  and  work  under 
many  different  conditions  of  head,  but  there  would  seem  to  be  no 
adequate  reason  why  the  gate  of  one  water-wheel  developing  a 
certain  amount  of  power  under  a  given  head  should  require  only 
1000  ft.-lbs.  to  completely  open  it,  and  the  gate  of  another  water- 
wheel  of  different  make,  developing  the  same  amount  of  power 
under  the  same  head,  should  require  60,000  ft.-lbs.  Yet  such  has 
been  found  to  be  the  case.  The  above  example,  taken  from  actual 
practice,  is  by  no  means  unusual ;  and  scores  of  such  cases  could  be 
cited  showing  relatively  absurd  figures. 

Some  builders  prefer  to  use  cylinder  gates  on  their  wheels; 
others  prefer  wicket  gates;  while  still  others  adhere  to  register 
.gates.  It  is  not  the  intention  of  this  paper  to  enter  into  a  critical 
comparison  of  the  merits  of  these  various  types  of  gate,  and  in  fact, 
from  the  standpoint  of  speed  regulation,  no  such  comparison  is 
necessary  for  the  good  and  sufficient  reason  that  there  are  wheels 
on  the  market  of  all  three  of  the  above  kinds  which  show  little  to  be 
desired  in  the  ease  with  which  the  gates  may  be  moved.  It  is  also 
true  that  there  are  makes  of  wheels  of  all  three  kinds  which  cannot 
be  governed  accurately  under  variable  loads,  simply  for  the  reason 
that  their  gates  cannot  be  moved  quickly  enough. 

It  is  often  necessary  to  start  a  gate  from  a  rest  and  completely 
open  or  close  it  in  2  or  3  seconds,  or  give  it  a  proportionately 
.smaller  motion  in  a  proportionately  shorter  space  of  time.  Or; 


226  APPENDIX. 

what  is  still  more  severe,  it  is  often  necessary  that  while  a  gate  is 
opening  or  closing,  its  motion  be  instantly  stopped  and  reversed. 

If  one  will  watch  a  thoroughly  first-class  governor  handling  the 
gates  of  a  water-wheel  which  is  driving  an  electric  generator  operat- 
ing on  a  variable  load,  one  is  convinced  of  the  fact  that  the  governor 
has  to  develop  considerable  amounts  of  energy  in  surprisingly  short 
spaces  of  time,  and  that  the  rigging  connecting  the  governor  and 
the  gates  is  subjected  necessarily  to  considerable  strain,  from  which 
it  follows  that  the  easier  the  gates  move  the  less  chance  there  is  of 
stripping  gears  and  twisting  off  shafts,  to  say  nothing  of  relieving 
the  governor  itself  of  unnecessary  strain. 

All  gears  between  governor  and  gate — except  immersed  racks 
and  pinions — should  be  cut,  of  first-class  workmanship,  and  not 
too  large  for  the  work  required  of  them.  The  latter  precaution  is 
necessary  to  prevent  the  MV2  energy  in  the  gears  themselves 
destroying  the  rigging  when  the  direction  of  motion  is  suddenly 
reversed.  Shafts  should  be  of  just  sufficient  size  to  give  an  ample 
factor  of  safety,  and  prevent  torsional  difficulties,  for  it  is  absolutely 
necessary  that  the  smallest  amount  of  motion  of  the  governor  shall 
be  transmitted  accurately  to  the  water-wheel  gate.  Lost  motion 
in  gears  and  twisting  of  shafts  are  fatal  to  good  regulation.  Hand- 
wheels  should  be  so  arranged  that  they  may  be  entirely  thrown  out 
of  connection  with  the  rigging  while  the  governor  is  in  action, 
or  they  may  be  unkeyed  in  some  simple  manner. 

Counterbalancing  a  gate  is  not  the  equivalent  of  having  it  in  water 
balance.  All  vertical  cylinder  gates  are  necessarily  out  of  balance 
to  an  amount  equal  to  their  immersed  weight,  but  that  is  usually  so 
small  that  it  is  not  necessary  to  counteract  it  with  a  counterweight. 

Some  designs  of  gate  show  a  violent  tendency  to  close  or  stay 
closed.  It  is  the  custom  to  counterbalance  such  gates,  and  this 
practice  leads  to  endless  trouble  on  account  of  the  kinetic  energy 
in  the  counterweight.  It  being  often  necessary  to  reverse  the 
motion  of  the  counterweight  suddenly,  the  kinetic  energy  expended 
at  the  moment  of  reversal  is  often  sufficient  to  wreck  the  rigging. 
If  counterweights  must  be  used,  it  should  be  remembered  that  their 
kinetic  energy  is  proportional  to  their  weight,  but  also  proportional 
to  the  square  of  their  velocities ;  from  which  it  follows  that  a  heavy, 
slow-moving  weight  does  less  damage  than  a  light,  rapid-moving  one.. 


APPENDIX.  227 

Some  general  statements  may  be  made  in  regard  to  the  design 
of  water-wheel  gates  adapted  to  plants  in  which  it  is  desirable  to 
obtain  good  speed  regulation. 

It  has  been  the  custom  of  late  to  cast  onto  cylinder  gates 
fingers  reaching  out  between  the  guides.  These  innocent-looking 
devices,  which  are  supposed  to  guide  the  water  into  the  wheel 
properly,  and  hence  raise  its  efficiency,  are  a  source  of  no  end  of 
trouble  when  it  comes  to  moving  the  gate  quickly  enough  to  produce 
good  speed  regulation.  The  direction  of  motion  of  the  water  as  it 
enters  the  wheel  is  always  such  that  it  presses  these  fingers  down- 
ward wkh  tremendous  force,  giving  the  gate  a  strong  tendency  to 
close.  By  removing  these  fingers,  the  amount  of  energy  necessary 
to  open  the  gates  can  always  be  reduced  by  at  least  one-half,  and 
oftentimes  more  than  that.  There  are  scores  of  water-wheels 
on  record  which  were  so  much  out  of  balance,  due  to  the  fingers  on 
the  gates,  that  it  was  found  impracticable  to  govern  them  satis- 
factorily on  account  of  gears  stripping  and  shafts  twisting  off.  In 
the  writer's  experience  it  has  always  been  found  practicable  to 
govern  these  wheels  by  removing  the  fingers. 

Now  as  to  the  question  of  efficiency.  The  writer  has  often 
had  to  meet  the  argument  of  the  few  per  cent  of  efficiency  supposed 
to  be  lost  by  removing  these  fingers,  and  to  answer  this  question 
tests  have  been  made  which  show  that  there  is  no  material  gain  in 
the  efficiency  of  a  water-wheel  set  under  ordinary  working  conditions 
by  attaching  fingers  to  the  gate. 

Two  vertical  cylinder-gate  wheels  of  the  same  size  and  make 
were  set  in  open  flumes  side  by  side.  The  head  was  precisely  the 
same  in  both  cases.  Both  wheels  drove  electric  generators  of  the 
same  make,  type,  and  size.  Both  wheels  were  furnished  by  the 
maker  with  cylinder  gates  precisely  like  and  provided  with  fingers. 
It  was  found  impracticable  to  govern  these  wheels  properly,  on 
account  of  the  gates  working  so  hard  and  being  so  much  out  of 
balance.  The  fingers  were  removed  from  the  gate  of  one  wheel, 
and  it  was  at  once  found  that  the  wheel  governed  very  satisfactorily 
under  a  very  variable  load.  Then  a  test  was  made  of  the  efficiency 
of  the  two  wheels,  one  with  and  one  without  fingers  on  the  gates. 
Wires  were  brought  up  from  the  gates,  carried  over  pulleys,  kept 
taut  by  small  weights,  and  they  terminated  in  pointers  reading  on 


228  APPENDIX. 

the  same  scale.  A  constant  electrical  load  was  switched  onto  one 
generator,  and  the  position  of  the  pointer  indicating  gate  position 
was  noted.  Then  the  load  was  switched  onto  the  other  generator 
(the  speed  being  kept  the  same  in  both  cases) ,  and  it  was  noted  that 
the  pointer  of  the  second  unit  stood  at  the  same  point  at  which  the 
pointer  of  the  first  unit  had  previously  stood.  This  experiment 
was  repeatedly  tried  at  a  number  of  different  loads,  from  slightly 
above  friction  load  to  nearly  the  full  capacity  of  the  wheels.  So 
far  as  could  be  observed,  the  efficiency  of  the  wheel  without  fingers 
on  the  gate  was  as  good  as  that  of  the  wheel  with  the  fingers.  The 
particular  test  above  described  was  made  by  Mr.  J.  H.  Wilson,  in 
the  plant  of  the  Berlin  Mills  Co.,  Berlin  Mills,  N.  H. 

The  writer  is  aware  that  this  test  is  not  the  equivalent  of  a 
Holyoke  test,  but  it  is  certainly  of  great  interest  to  the  practical 
engineer  who  is  harassed  by  the  thought  that  in  avoiding  the  Scylla 
of  bad  efficiency  he  will  surely  be  wrecked  on  the  Charybdis  of  an 
ungovernable  gate. 

There  are  a  number  of  other  details  of  cylinder-gate  construction 
which  time  and  space  will  not  permit  us  to  touch  upon  here,  but 
which  should  be  considered  by  the  thoughtful  engineer  before  making 
a  selection.  The  thing  to  be  borne  in  mind  is  that  the  cylinder  and 
its  connections  should  be  of  such  design  that  they  may  be  easily 
moved,  and  will  not  bind  and  run  hard  in  any  portion  of  their  travel. 

Wicket  gates  also  have  their  pecularities.  Some  makers  hang 
them  in  such  a  manner  that  they  are  practically  in  water  balance 
in  any  position,  and  may  be  readily  opened  and  closed  with  a  small 
expenditure  of  energy.  Such  gates  leave  little  to  be  desired,  and 
wheels  fitted  with  gates  so  designed  may  be  governed  with  the 
greatest  degree  of  exactness  and  without  fear  of  injury  to  the 
rigging  or  governor.  The  writer  has  observed,  however,  that  some 
wicket  gates  which  move  very  easily  have  so  much  lost  motion  that 
in  certain  portions  they  tend  to  flop  (no  other  word  conveys  the 
idea)  first  in  one  direction  and  then  in  the  other,  causing  a  pulsating 
speed  which  is  very  annoying  and  apparently  inexplicable  until 
one  has  investigated  the  cause.  The  danger  of  lost  motion  is 
greater  with  wicket  than  with  cylinder  gates,  but  with  proper 
construction  it  is  found  in  practice  that  lost  motion  may  be  entirely 
eliminated  from  wicket  gates. 


APPENDIX.  229 

In  some  wicket-gate  wheels  the  wickets  are  hinged  at  one  end 
and  attached  by  the  other  end  by  tangential  arms  to  a  banjo,  which 
in  turn  is  geared  to  the  shaft  going  to  the  governor.  Such  gates 
are  entirely  out  of  water  balance  when  partly  closed,  and  the  more 
they  are  closed  the  more  they  are  out  of  balance.  Wheels  with 
gates  of  this  description  are  very  difficult  to  govern.  Frequently 
the  strength  of  the  wickets  and  radial  arms  is  not  sufficient  to 
withstand  the  water-pressure,  even  if  sufficient  energy  can  be  sup- 
plied-to  them.  In  recent  practice  a  wheel  of  this  description  was 
found  to  require  some  40,000  ft.-lbs.  to  open  it.  Another  wicket- 
gate  wheel  of  different  make  but  the  same  rated  horse-power  was 
found  to  require  only  5000  ft.-lbs.  to  open  it.  As  another  recent 
instance,  it  was  found  that  a  pair  of  wicket-gate  wheels  of  the 
kind  described  above  required  19,000  ft.-lbs.  to  open  them;  another 
pair  of  different  make  but  the  same  rated  horse-power  required 
but  2500  ft.-lbs.  to  open  them.  The  wheels  compared  above  were 
working  under  the  same  head. 

The  way  a  maker  proposes  to  rig  his  gate  is  a  good  indication 
of  the  amount  of  energy  he  thinks  it  will  take  to  move  it.  If  he 
thinks  it  is  necessary  to  use  worm-gears  or  multiplying-gears  giving 
a  large  number  of  turns  to  the  hand- wheel,  it  is  safe  to  conclude 
that  in  his  opinion — and  he  certainly  ought  to  know — the  gate 
will  move  hard  or  be  much  out  of  balance.  Such  wheels  it  is  safe 
to  leave  alone  if  accurate  speed  regulation  under  variable  load  is 
the  end  in  view. 

All  practical  engineering  is  a  compromise  between  the  desire  of 
the  engineer  on  the  one  hand  to  produce  a  perfect  piece  of  engineer- 
ing and  the  unwillingness  of  the  stockholders  on  the  other  hand 
to  invest  money  which  will  not  bring  direct  returns  in  the  shape  of 
dividends,  or,  to  state  the  matter  more  conservatively,  there  is 
always  a  point  in  each  plant  beyond  which  investment  must  not 
.go,  and  this  point  is  different  for  each  plant,  being  fixed  by  the 
economic  conditions  which  surround  the  particular  enterprise. 

For  the  above  reasons  it  is  impossible  to  lay  down  hard  and 
fast  rules  for  the  development  of  water-powers.  Assuming  that 
the  value  of  all  engineering  is  measured  by  the  dividends  earned, 
what  would  be  good  engineering  in  one  case  is  bad  engineering  in 
another.  Yet  it  is  equally  true  that  in  an  electric  plant  driven 


230  APPENDIX. 

by  water-power  the  worst  possible  place  to  economize  is  in  the 
channels  and  conduits  which  bring  the  water  to  and  away  from 
the  water-wheels,  and  in  the  water-wheels  themselves  and  their 
governors.  Dollars  saved  here  are  apt  to  be  expensive  economy. 
The  infinite  variety  in  which  natural  water-powers  present 
themselves  makes  this  a  difficult  branch  of  engineering,  and  much 
is  yet  to  be  learned  about  it.  Yet  it  is  safe  to  say  that  enough  is 
now  known  about  the  subject  to  permit  almost  any  naturally 
good  water-power  to  be  so  developed  and  utilized  that  the  plant 
driven  by  it  may  be  as  readily  controlled  and  its  speed  maintained 
as  constant  as  though  the  driven  load  were  carried  by  first-class 
steam-engines.  It  should,  however,  be  remembered  that,  no  matter 
how  well  the  plant  is  designed,  good  speed  regulation  cannot  be 
obtained  unless  the  water-wheel  governors  are  of  correct  design 
and  well  built.  The  value  of  a  governor  is  measured  by  two  things 
— the  promptness  and  ease  with  which  it  will  move  the  water- 
wheel  gates  to  the  correct  position  and  stop  them  when  they  get 
there,  and  its  ability  to  compensate  by  adjustment  of  the  gate  for 
the  kinetic  energy  in  the  moving  water-column.  One  might  add 
sensitiveness  as  a  mark  of  a  good  governor,  but  nearly  all  modern 
governors  are  very  sensitive,  though  most  of  them  sadly  lack  the 
other  two  qualifications  named  above.  The  best  made  governors 
on  the  market  will  begin  to  move  the  water-wheel  gates  before  any 
tachometer  on  the  market  will  show  a  change  in  speed,  yet  they 
would  not  govern  if  they  did  not  know  when  to  stop  as  well  as 
when  to  start. 

I  have  been  requested  by  a  number  of  gentlemen  to  say  some- 
thing about  fly-wheels.  We  may  approach  this  subject  in  the 
following  manner: 

When  we  wish  to  find  out  how  much  energy  is  stored  in  a  re- 
volving fly-wheel  we  begin  by  finding  its  moment  of  inertia,  which, 
is  its  weight  multiplied  by  the  square  of  its  radius  of  gyration. 
Let  J= radius  of  gyration  in  feet; 
W= weight  in  pounds; 
/= moment  of  inertia. 

I=WJ2. (19) 


APPENDIX.  231 

The  energy  in  foot-pounds  stored  in  the  revolving  wheel  is  as 
follows: 

Let  8  =  energy  stored  in  the  wheel; 

a  =  angular  velocity  in  radians  per  second  =-TJT,  .     .     (20) 

OU 

where    n=  revolutions  per  minute 
and    7r  =  3.14159.    Then 


-.  .:,;  .        •-   .............  (2D 

Substituting  the  value  of  a  we  get 


(22) 

£g 

Evolving  which  we  get 

8=S' <23> 

which  is  the  form  in  which  the  formula  is  ordinarily  used. 
It  may  be  simplified,  for 

2 

T™=. 00551  is  a  constant. 

J-O\J\J 

Substituting  this  we  get 

&  =  In2X.  00551 (24) 

But  you  will  note  that  this  expression  may  be  conveniently 
•divided  into  two  parts,  as  follows: 

£  =  n2X(/X.  00551), (25) 

which  is  equivalent  to  saying  that  every  fly-wheel  possesses  a 
certain  quantity  which,  multiplied  by  the  square  of  its  revolu- 
tions per  minute,  equals  the  foot-pounds  of  energy  stored  in  it. 


232  APPENDIX. 

This  quantity  is  its  (7  X.  00551),  which  we  may  symbolize  by  3TC  and 
we  may  write 


.     .     .     ...     .     .     (26) 

Or,  substituting  our  value  of  I,  we  may  write 

.00551).       .    .     ...     (27) 


It  is  evident  that  this  value  of  3H,  which  is  the  energy  stored 
in  the  wheel  when  making  one  revolution  per  minute,  when  once 
found  for  any  particular  fly-wheel  may  be  used  at  once  to  calculate 
its  energy  at  any  speed,  simply  by  multiplying  it  by  the  square  of 
its  revolutions  per  minute. 

This  value  of  2flX  for  the  rim  of  any  fly-wheel  may  be  found  as 
follows  : 

Let  w=  weight  in  pounds  of  1  cu.  ft.  of  the  metal  of  which  it  is 

made; 

d=  outside  diameter  of  rim  in  feet; 
d\  =  inside  diameter  of  rim  in  feet; 
1=  face  of  rim  in  feet.    Then 


59,814 

But  a  close  enough  approximation  to  the  3TC  of  a  cast-iron  fly- 
wheel of  usual  shape  with  light  arms  may  be  found  as  follows  : 

Let  W=  weight  of  wheel  in  pounds; 
d=  mean  diameter  of  rim.     Then 


3K—        -  (29) 

"  23,000' 

Now  the  question  is  how  much  of  a  fly-wheel  do  we  require  in 
any  particular  case.  Let  us  return  to  wheel  No.  1  in  Fig.  4. 

We  remember  that  when  the  gate  of  this  wheel  was  suddenly 
opened  wide  it  was  .7  second  before  the  water  was  doing  its  full 


APPENDIX.  233 

amount  of  work  on  the  runner.  We  must  also  remember  that  the 
curve  0-1  (see  Fig.  7)  with  which  the  water  got  up.  to  full  power 
was  a  parabola.  The  area  outside  the  parabolic  line  was  the  work 
which  the  water  did  do  in  this  .7  second,  and  the  area  inside  this 
parabolic  line  was  the  work  which  the  water  failed  to  do  in  the 
same  time.  From  the  law  of  areas  of  parabolas  it  follows  that 
the  area  inside  this  curve  (which  is  a  half-parabola)  is  two-thirds 
of  the  area  of  the  rectangle  enclosing  the  curve.  Or  we  may  say 
more  simply  that  while  the  wheel  was  getting  up  to  speed  it  per- 
formed one-third  of  the  work  which  it  would  have  done  in  the 
same  time  had  it  been  working  at  full  gate  and  full  speed. 

Let  us  begin  to  apply  this  to  the  design  of  a  suitable  fly-wheel. 
Assume,  for  simplicity  of  calculation,  that  the  water-wheel  is  about 
48  ins.  in  diameter  and  at  full  gate  develops  100  H.P.  and  runs 
at  75  R.P.M.  Let  us  also  assume  that  it  must  not,  upon  the  whole 
load  being  instantly  thrown  on  or  off,  run  more  than  4%  below 
or  above  normal.  Its  minimum  speed  must  be  then 


and  its  maximum  speed  must  be 

75  +^^=78  R.P.M. 

iuu 

We  must  also  remember  that  it  was  found  that  we  could  not 
completely  open  the  gates  in  less  than  2  seconds.  Therefore, 
supposing  that  the  rate  of  opening  the  gate  was  uniform,  the 
average  gate-opening  during  the  2  seconds  was  only  ome-half  ,  and 
if  the  wheel  during  every  instant  of  time  had  been  developing 
the  full  power  due  to  the  instantaneous  value  of  gate-opening, 
it  would  have  developed  only  one-half  as  many  foot-pounds  as 
though  it  had  been  at  full  gate  for  2  seconds.  But  we  found  that 
the  power  lagged  .7  second  behind  the  gate-opening,  during  which 
time  it  developed  only  one-third  of  the  power  due  to  the  gate- 
opening;  hence  for  2  seconds  the  wheel  developed  £  of  J  the  power 
it  would  have  developed  during  the  same  time  at  full  gate,  and  for 


23  i  APPENDIX. 

.7  second  more  it  developed  one-third  of  full  power.     Reducing 
this  to  foot-pounds,  we  have 

100X550X2 

~6~~  18,333  ft.-lbs., 

iooxfrox.7_12>833    ., 

O  

Adding  these  we  get  31,166  ft.-lbs.,  which  is  the  total 

energy  developed  by  the  water-wheel  in  2.7  seconds. 

If  working  at  full  gate  and  maximum  flume  velocity  for  that 
length  of  time  it  would  have  developed 

100X550X2.7=110,000  ft.-lbs. 
Subtracting  from  this  31,166     ' ' 


we  get  78,834  ft.-lbs.,    which    is    the 

amount  of  energy  which  must  be  developed  by  the  fly-wheel  before 
its  speed  is  reduced  to  72  R.P.M. 

Let  us  assume  that  the  fly-wheel  makes  the  same  number  of 
revolutions  as  the  water-wheel. 

Its  energy  at  75  R.P.M.  is 


Its  energy  at  72  R.P.M.  is 


Subtracting  one  from  the  other  we  get  441 
The  value  of  3TC  is  therefore 


441 

From  the  above  value  of  2flt  should  be  deducted  the  3TC  of  the 
water-wheel  itself  and  the  other  rotating  parts,  such  as  pulleys 
and  armatures.  For  simplicity  of  calculation  I  shall  not  make 
this  deduction  in  this  case,  and  we  will  proceed  to  design  a  fly- 


APPENDIX.  235 

wheel  of  suitable  proportions,  which  shall  have  an  31Z  value  numeri- 
cally equal  to  178. 

As  it  is  to  be  of  cast-iron  we  will  limit  its  peripheral  speed  to 
65  ft.  per  second. 

Let  d=its  outside  diameter  in  feet; 

p=its  peripheral  speed  in  feet  per  second; 
R=  revolutions  per  minute.    Then 


Applying  numerical  values  we  get 
65X60 


Applying  numerical  values  we  get 
178X59,814 


Assume  d\  or  the  diameter  inside  the  rim  =14.5  ft. 
Transpose  formula  No.  28  so  as  to  get  I  or  the  face  of  the  wheel 
in  feet. 

9TIX59,814 
*- 


=  1  ft"  7  m" 


Our  fly-wheel  rim  is,  therefore,  15  ft.  6  ins.  outside  diameter, 
6  ins.  thick,  and  1  ft.  7  ins.  wide  on  the  face,  and  would  weigh 
16,992  Ibs. 

This  strikes  one  as  a  very  large  fly-wheel  for  a  100-H.P.  unit, 
but  it  must  be  remembered  that  it  is  intended  to  perform  very 
severe  duty.  Moreover,  no  allowance  has  been  made  for  the 
kinetic  energy  in  the  fly-wheel  arms,  nor  in  the  water-wheel  itself 
and  other  rotating  parts.  All  of  these  corrections  should  be  made 
and  the  proper  deduction  made  from  the  fly-wheel  above  designed. 

Another  correction  should  also  be  made  which  would  still  further 
reduce  the  size  of  the  fly-wheel. 

It  was  assumed  that  the  water-wheel  was  working  at  normal 


236  APPENDIX. 

speed  and  friction  load  when  the  whole  load  was  thrown  on.  Fric- 
tion load  is  a  part  of  whole  load,  and  hence  when  we  say  we  throw 
on  whole  load,  we  really  mean  that  we  are  throwing  on  something 
less  than  100  H.P.  Also,  at  friction  load  the  water  in  the  flume 
had  some  velocity,  and  hence  we  did  not  have  to  start  the  water 
from  a  condition  of  rest,  but  from  a  condition  of  slow  velocity. 

To  make  all  these  corrections  involves  a  considerable  knowledge 
of  hydraulics  and  mechanics.  To  treat  this  subject  in  a  complete 
manner  would  involve  a  good  many  figures,  and  would  extend 
this  paper  far  beyond  proper  limits. 

It  may  be  noted  here  that  if  it  is  found  desirable  to  change  the 
value  of  2ftl  of  a  fly-wheel  after  it  is  designed,  it  is  not  necessary 
to  redesign  the  wheel.  The  dimensions  of  fly-wheels  are  as  the 
fifth  roots  of  their  3TC's.  We  have  found  a  fly-wheel  whose  2fft=  178. 
If  we  now  wish  to  reduce  its  2flZ  to  150,  we  write 

1/178  :  |/I50  =  15.5  :  diameter. 

From  which  we  get 

4/150X15.5       KA., 
diameter  =  - — r-= —  =  15.0  ft., 

or  formularizing  it  we  get 


where  D  =  diameter  of  wheel  having  given  3TC, 
DI  =  diameter  of  required  wheel, 
£(TC  =  given  value  of  3TC, 
2fTZi  =  required  value  of  SfliL 

All  of  the  linear  dimensions  should  be  treated  in  the  same  way. 
For  example:  if  we  have  a  design  of  a  fly-wheel  drawn  to  a  scale 
of  1  in.  to  the  foot,  and  in  building  the  wheel  we  read  the  drawing 
as  though  it  were  £  in.  to  the  foot,  then  the  3TC  of  the  fly-wheel  will 
be  25= 32  times  as  large  as  it  would  have  been  if  the  wheel  had  been 
built  according  to  the  scale  of  1  in.  to  the  foot. 


APPENDIX.  237 

Where  we  have  a  fly-wheel  of  a  given  2fTC  and  we  know  how  many 
foot-pounds  it  will  be  required  to  give  up  or  absorb,  as  the  case  may 
be;  we  may  find  the  resulting  speed  by  the  following  formula : 


(32) 


where  r=the  final  revolutions  per  minute, 

&  =  energy  in  foot-pounds  stored  in  wheel  at  normal  speedr 
&  1  =  energy  in  foot-pounds  required  of  the  wheel, 
3TC  =  energy  in  wheel  when  making  one  revolution  per  minute, 


The  above  formula  may  be  more  conveniently  written  as  follows  : 

-Si 
sn, 


/ 
SI 


where  R=  normal  revolutions  per  minute.     Applying  to  the  wheel 
we  have  been  discussing  we  have 


I  (178  X752)-  78,834 


which  is  the  minimum  revolutions  per  minute  which  we  first  agreed 
upon. 

We  have  seen  that  to  make  even  an  approximate  design  of  fly- 
wheel we  have  required  considerable  data  to  work  from,  and  have 
been  obliged  to  do  quite  a  little  figuring,  and  yet  the  water-wheel 
in  question  was  set  in  the  simplest  possible  manner.  Had  it  been 
set  in  a  closed  flume  like  wheel  No.  2  (Fig.  4),  the  problem  would 
have  been  greatly  complicated. 

In  view  of  these  facts,  it  becomes  quite  amusing  to  note  the 
alleged  accuracy  with  which  statements  are  often  made  in  regard 
to  the  exact  amount  of  fly-wheel  which  is  required  to  give  stated 
degrees  of  speed  regulation  upon  10%,  25%,  50%,  etc.,  of  the  load 
being  instantly  thrown  off  or  on,  when  it  is  perfectly  evident  that 
only  part  of  the  data  is  available  which  would  enable  only  approxi- 
mate figures  to  be  made. 


238  APPENDIX. 

The  one  concluding  crumb  of  comfort  which  the  writer  is  able 
to  offer  is  found  in  the  fact  that  in  a  very  large  practice  he  has 
never  found  it  necessary,  with  a  water-wheel  set  in  an  open  flume, 
to  install  a  fly-wheel  in  order  to  obtain  a  perfectly  satisfactory 
speed  regulation  under  any  operating  conditions  of  an  electric 
plant.  The  various  rotating  parts  of  the  plant,  such  as  water- 
wheels,  ai matures,  pulleys,  etc.,  having  sufficient  moment  of  inertia 
and  angular  velocity  to  enable  a  first-class  governor  to  hold  the 
speed  within  very  satisfactory  limits  under  any  sudden  load  changes 
which  occur  in  the  actual  operation  of  the  plant. 

If  the  design  of  the  hydraulic  part  of  the  plant  is  bad,  it  is  wiser 
to  try  and  improve  it  rather  than  lean  largely  on  fly-wheel  effect- 
which  is  a  weak  prop  at  the  best. 


CIVIL  ENGINEERING 

U.  ol  C. 
ASSOCIATION  LIBRARY 


INDEX. 


PACK 

Action  turbines,  advantages  of 53 

disadvantages  of 53 

efficiencies  of $ 

theory  of 49 

Advantages  of  action  turbines 53 

limit  turbines 55 

reaction  turbines 49 

steam-turbines 59 

vertical  dynamos 74 

vertical  turbines 74 

Air-admission  valves 8, 109 

Air-chambers 145, 224 

as  an  aid  to  speed  regulation 145, 224 

Air-inlets  for  penstocks 172 

American  turbine-builders,  lack  of  progress  among 30 

practice 17 

American  turbines  as  hydraulic  motors 19 

as  machines 27 

Anchor-ice 190 

Bearings,  thrust- 81 

Books  and  papers  referred  to  in  foot-notes v 

Brake-governors 146 

British  and  metric  measures  and  value.8 199 

Buried  penstocks - 177 

By-pass 143 

as  an  aid  to  speed  regulation 143 

temporary 115, 144, 155 

Chamber,  air- 145, 224 

thrust- 11, 81 

Classification  of  turbines 37 

Comparison  of  American  and  French  vortex  turbines 25 

American  and  German  turbine  tests 32 

239 


.240  INDEX. 

PAG  a 

Comparison  of  steam-turbines 71 

steam-  and  hydraulic  turbines 57 

turbines 55 

Concrete  penstocks 179 

Conductors,  water- 161 

Construction  of  modern  turbines 73 

turbines  in  general 73 

Cost  of  water-power 196 

Curtis  steam-turbine 69 

Cylinder  gate 5, 18 

Deflecting-nozzle 114 

De  Laval  steam-turbine 66 

•Designing  of  turbines 120 

Developing  of  water-power 180 

Development,  efficiency  of  a 182 

of  turbines  in  America 17 

of  turbines  in  Europe 1 

Disadvantages  of  action  turbines 53 

reaction  turbines 49 

steam-turbines 61 

Draft-heads,  greatest 129 

Draft-tubes 123 

Draft-tube,  effect  of  the 123 

flare  of  the 128 

theory  of  the 123 

Drawings  of  turbines xxi 

Effect  of  the  draft-tube 123 

Efficiencies  of  action  turbines 5 

European  reaction  turbines 8 

limit  turbines 56 

reaction  turbines 8,  47,  56 

Efficiency  of  a  development 182 

tests  of  dynamos. 185 

tests  of  turbines 31, 185 

Elements  of  design  favorable  to  speed  regulation  of  turbines 203 

End  thrust  of  turbines 8,  80 

European  reaction  turbines,  efficiency  of 8 

turbine  practice 1 

Expansion  of  penstock 173 

Filter  for  hydraulic  governors 151 

Flare  of  draft-tubes 128 

Fly-wheels  as  an  aid  to  speed  regulation 145, 2CO 

Frazil-ice 192 


INDEX.  241 

PAGE 

Gages 137 

Gates,  cylinder 5, 18 

effect  of,  on  reaction  turbines 47 

head- 165 

register 6, 19 

wicket 7, 19 

Governor  relay 146 

Governors  and  speed  regulation 139 

brake- 146 

filters  for  hydraulic 151 

with  hydraulic  relay 151 

with  mechanical  relay 148 

Greatest  draft-heads .' 129 

Head-gates 165 

Headrace  and  tailrace 161 

High-head  turbines 108 

Hydraulic  relay  governors 151 

Ice 187 

anchor 190 

frazil 192 

surface 189 

Impulse  turbines 51, 113 

Lack  of  progress  among  American  turbine-builders 30 

Least  depths  of  water  above  turbines 93, 130 

Limit  turbines,  advantages  of 55 

efficiencies  of 56 

theory  of 54 

Losses  in  reaction  turbines 47 

Loss  of  head  in  penstock 170 

Low-head  turbines 83 

Manufacture  of  turbines 119 

Margin  of  power  required  for  speed  regulation 184 

Maximum  draft-head 129 

Measurement  of  water  for  selling  power 193 

Mechanical  relay  governors 148 

Medium-head  turbines 95 

Metric,  British  and,  measures  and  values 199 

Minimum  depth  of  water  above  turbines 93, 130 

Modern  turbine  types  and  their  construction 73 

Needle-nozzle 114 

Nomenclature  for  hydraulic  power  engineering xiii 


242  INDEX. 

PAGE 

Nozzles,  deflecting- 114 

needle- 114 

tongue- 115 

Open  turbine  chambers 89, 130, 222 

Parsons  steam-turbine , 62 

Penstocks 169 

air-inlets  for 172 

buried  in  the  ground 177 

concrete 179 

expansion  of 173 

loss  of  head  in 170 

piers 175 

speed  ol  water  in 170 

steel 173 

wooden 178 

Piers  for  penstocks 175 

Piston,  thrust 9, 81 

Present  turbine  practice  in  America 19, 27 

in  Europe 5 

Pressure  relief-valves 141 

Pump  suction 125 

Pumps,  turbine- 13 

Rateau  steam-turbine 69 

Racks 163 

Reaction  turbines,  advantages  of 49 

disadvantages  of 49 

effect  of  gates  on 47 

efficiencies  of 8, 47,  56 

losses  in 47 

theory  of 38 

Reference-books  and  papers  named  in  foot-notes V 

Register  gate 6, 19 

Relay  for  speed  governors 146 

Relief -valves,  hydraulic 141 

spring 141 

Rheostat,  water- 186 

Specifications  for  turbines.     See  turbine  construction  in  general,  also 
turbines  for  low,  medium,  and  high  heads. 

Speed  of  water  in  penstocks 170 

Speed  regulation,  air-chambers  as  an  aid  to 145,  224 

by  throttling-gates 134 

elements  favorable  to 203 


INDEX.  243 

PAGE 

Speed  regulation,  fly-wheels  as  an  aid  to 145, 230 

margin  of  power  required  for 184 

of  turbines 139, 203 

stand-pipes  as  an  aid  to 144, 220 

the  by-pass  as  an  aid  to 143 

the  temporary  by-passes  as  an  aid  to 144 

Spoon-turbine 1 13 

Stand-pipes 144, 220 

as  an  aid  to  speed  regulation 144,  220 

Steam-turbine,  Curtis 69 

De  Laval 66 

Rateau 69 

Westinghouse-Parsons 62 

.Steam-turbines 57 

advantages  of 59 

comparison  of < . .     71 

comparison  with  hydraulic  turbines 57 

disadvantages  of 61 

Steel  penstocks 173 

Stop-valves  for  turbines 132 

Suction  of  pumps 125 

Surface-ice 189 

Symbols  for  hydraulic  power  engineering xiii 

Tailrace,  headrace  and 161 

Temporary  by-pass 115, 144, 155 

as  an  aid  to  speed  regulation 144 

Terms  for  hydraulic  power  engineering xiii 

Tests,  efficiency,  of  dynamos 185 

of  turbines 185 

Theory  of  action  turbines 49 

draft-tubes 123 

limit  turbines 54 

reaction  turbines 38 

speed  regulation  of  turbines 139,  203 

Throttling-gates  for  speed  regulation 134 

Thrust-bearings 81 

chamber 11, 81 

end-,  of  turbines 8,  80 

piston 9, 81 

Tongue  nozzle 115 

Turbine  chambers,  open 89, 130, 222 

construction  in  general 73 

designing 120 

development  in  America 17 


244  INDEX. 


PAGE 

Turbine  development  in  Europe „  1 

drawings xxi 

manufacture 119 

practice  in  America 17 

practice  in  Europe 1 

practice,  present,  in  America 19, 27 

practice,  present,  in  Europe 5 

pumps 13 

specifications.     See  turbine  construction  in  general,  also  tur- 
bines for  low,  medium,  and  high  heads. 

tests,  comparison  of  American  and  German 32 

Turbines,  action 49 

classification  of 37 

comparison  of 55 

for  high  heads 108 

for  low  heads 83 

for  medium  heads 95 

impulse 51, 113 

least  depth  of  water  above 93, 130 

limit 54 

reaction 38 

spoon- 113 

steam- 57 

theory  of 37 

Valves,  air-admission 8,  109 

hydraulic  relief- 141 

spring  relief- 141 

stop-,  for  turbines 132 

Vents,  air-,  for  penstocks 172 

Vertical  dynamos,  advantages  of 74 

turbines,  advantages  of 74 

Vortex  turbines,  comparison  of  American  and  French 25 

Water  above  turbines,  least  depth  of 93, 130 

-conductors 161 

measurements  for  selling  power 193 

-power,  cost  of 196 

-power,  developing  a   180 

-racks 163 

-rheostat 186 

Westinghouse-Parsons  steam-turbine 62 

Wicket  gate 7, 19 

Wooden  penstocks 178 

Zodel  register  gate 0 


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BECKWITH,  A.     Pottery.     Observations  on  the  Materials 

and  Manufacture  of  Terra-cotta,  Stoneware,  Firebrick,  Porce- 
lain, Earthenware,  Brick,  Majolica,  and  Encaustic  Tiles.  Second 
Edition.  8vo,  paper 60 

BEGTRUP,  J.,  M.E.      The  Slide  Valve  and  its  Functions. 

With  Special  Reference  to  Modern  Practice  in  the  United  States. 
With  numerous  diagrams  and  figures.  8vo,  cloth $2 . 00 

BERNTHASEN,  A.      A  Text-book  of  Organic  Chemistry. 

Translated  by  George  M'Gowan,  Ph.D.  Fifth  English  Edition, 
revised  and  extended  by  author  and  translator.  Illustrated. 
12mo,  cloth In  Press. 

BERRY,  W.  J.  Differential  Equations  of  the  First  Species. 
12mo,  cloth,  illustrated In  Press, 


6  D.  VAN  NOSTRAND  COMPANY'S 

BERSCH,   J.,    Dr.      Manufacture    of   Mineral    and   Lake 

Pigments.  Containing  directions  for  the  manufacture  of  all 
artificial  artists'  and  painters'  colors,  enamel  colors,  soot  and 
metallic  pigments.  A  text-book  for  Manufacturers,  Merchants, 
Artists  and  Painters.  Translated  from  the  second  revised  edition 
by  Arthur  C.  Wright,  M.A.  8vo,  cloth,  illustrated net,  $5.00 

BERTIN,  L.  E.      Marine  Boilers:   Their  Construction  and 

Working,  dealing  more  especially  with  Tubulous  Boilers.  Trans- 
lated by  Leslie  S.  Robertson,  Assoc.  M.  Inst.  C.  E.,  M.  I.  Mech.  E., 
M.I.N.A.,  containing  upward  of  250  illustrations.  Preface  by 
Sir  William  White,  K.C.B.,  F.R.S.,  Director  of  Naval  Construc- 
tion to  the  Admiralty,  and  Assistant  Controller  of  the  Navy. 
Second  Edition,  revised  and  enlarged.  8vo,  cloth,  illustrated. 

net ,  $5 . 00 

BIGGS,   C.   H.   W.       First  Principles   of  Electricity   and 

Magnetism.  A  book  for  beginners  in  practical  work,  containing 
a  good  deal  of  useful  information  not  usually  to  be  found  in 
similar  books.  With  numerous  tables  and  343  diagrams  and 
figures.  12mo,  cloth,  illustrated $2 .00 

BINNS,  C.  F.      Ceramic  Technology.     Being  Some  Aspects 

of  Technical  Science  as  applied  to  Pottery  Manufacture.  8vo, 
cloth net,  $5.00 

Manual  of  Practical  Potting.      Compiled  by  Experts. 

Third  Edition,  revised  and  enlarged.     8vo,  cloth net,  $7 . 50 

BIRCHMORE,  W.  H.,  Dr.      How  to  Use  a  Gas  Analysis. 

12mo,  cloth,  illustrated net,  $1 . 25 

BLAKE,  W.  H.     Brewer's  Vade  Mecum.     With  Tables  and 

marginal  reference  notes.     8vo,  cloth net,  $4 . 00 

W.  P.     Report    upon    the    Precious    Metals.     Being 

Statistical  Notices  of  the  Principal  Gold  and  Silver  producing 
regions  of  the  world,  represented  at  the  Paris  Universal  Exposi- 
tion. 8vo,  cloth $2. 00 

BLAKESLEY,  T.  H.     Alternating  Currents  of  Electricity. 

For  the  use  of  Students  and  Engineers.  Third  Edition,  enlarged. 
12mo,  cloth $1 .50 

BLYTH,  A.  W.,  M.R.C.S.,  F.C.S.  Foods:  Their  Com- 
position and  Analysis.  A  Manual  for  the  use  of  Analytical 
Chemists,  with  an  Introductory  Essay  on  the  History  of  Adultera- 
tions. With  numerous  tables  and  illustrations.  Fifth  Edition, 
thoroughly  revised,  enlarged  and  rewritten.  8vo,  cloth $7.50 


SCIENTIFIC  PUBLICATIONS.  7 

BLYTH,  A.  W.,  M.R.C.S.,  F.C.S.,  Poisons:  Their  Effects  and 

Detection.  A  Manual  for  the  use  of  Analytical  Chemists  and 
Experts,  with  an  Introductory  Essay  on  the  Growth  of  Modern 
Toxicology.  New  Edition In  Press. 

BODMER,  G.  R.     Hydraulic  Motors  and  Turbines.     For 

the  use  of  Engineers,  Manufacturers  and  Students.  Third  Edi- 
tion, revised  and  enlarged.  With  192  illustrations.  12mo, 
cloth $5.00 

BOILEAU,  J.  T.    A  New  and  Complete  Set  of  Traverse 

Tables,  showing  the  Difference  of  Latitude  and  Departure  of 
every  minute  of  the  Quadrant  and  to  five  places  of  decimals. 
8vo,  cloth $5 . 00 

BONNEY,     G.    E.      The     Electro-platers'   Handbook.      A 

Manual  for  Amateurs  and  Young  Students  of  Electro-metallurgy. 
60  illustrations.  12mo,  cloth $1 . 20 

BOOTH,  W.  H.  Water  Softening  and  Treatment,  Con- 
densing Plant,  Feed  Pumps,  and  Heaters  for  Steam  Users  and 
Manufacturers.  8vo,  cloth,  illustrated net,  $2 . 50 

BOURRY,  E.     Treatise  on  Ceramic  Industries.    A  Complete 

Manual  for  Pottery,  Tile  and  Brick  Works.  Translated  from 
the  French  by  Wilton  P.  Rix.  With  323  figures  and  illustrations. 
8vo,  cloth,  illustrated net,  $8 . 50 

BOW,  R.  H.  A  Treatise  on  Bracing.  With  its  applica- 
tion to  Bridges  and  other  Structures  of  Wood  or  Iron.  156  illus- 
trations. 8vo,  cloth SI .  50 

BOWIE,  AUG.  J.,  Jr.,  M.E.      A    Practical    Treatise   on 

Hydraulic  Mining  in  California.  With  Description  of  the  Use 
and  Construction  of  Ditches,  Flumes,  Wrought-iron  Pipes  and 
Dams;  Flow  of  Water  on  Heavy  Grades,  and  its  Applicability, 
under  High  Pressure,  to  Mining.  Ninth  Edition.  Small  quarto, 
cloth.  Illustrated $5.00 

BOWKER,  Wm.   R.      Dynamo,   Motor   and   Switchboard 

Circuits.  For  Electrical  Engineers.  A  practical  book,  dealing 
with  the  subject  of  Direct,  Alternating,  and  Polyphase  Currents. 
With  over  100  diagrams  and  engravings.  8vo,  cloth. .  net,  $2.25 

BOWSER,    E.    A.,    Prof.     An    Elementary    Treatise    on 

Analytic  Geometry.  Embracing  Plane  Geometry,  and  an  Intro- 
duction to  Geometry  of  three  Dimensions.  Twenty-first  Edition. 
12mo,  cloth net,  $1 . 75 


8  D.  VAN  NOSTRAND  COMPANY'S 

BOWSER,  E.  A.,   Prof.     An   Elementary  Treatise   on  the 

Differential  and  Integral  Calculus.  With  numerous  examples. 
Twenty-first  Edition.  Enlarged  by  640  additional  examples. 
12mo,  cloth net,  $2.25 

An  Elementary  Treatise  on  Analytic  Mechanics.  With 

numerous  examples.     Sixteenth  Edition.     12mo,  cloth,  .net,  $3.00 

An  Elementary  Treatise  on  Hydro-mechanics.     With 

numerous  examples.     Fifth  Edition.     12mo,  cloth net,  $2 . 50 

A  Treatise  on  Roofs  and  Bridges.     With  Numerous 

Exercises,  especially  adapted  for  school  use.  12mo,  cloth. 
Illustrated net,  $2.25 

BRASSEY'S   Naval   Annual   for   1906.     Edited   by   T.   A. 

Brassey.  With  numerous  full-page  diagrams,  half-tone  illustra- 
tions and  tables.  Twentieth  year  of  publication.  8vo,  cloth, 
illustrated net,  $6.00 

BRAUN,  E.     The  Baker's  Book:    A  Practical  Handbook 

of  the  Baking  Industry  in  all  Countries.  Profusely  illustrated 
with  diagrams,  engravings,  and  full-page  colored  plates.  Trans- 
lated into  English  and  edited  by  Emil  Braun.  Vol.  I.,  8vo, 

cloth,  illustrated,  308  pages $2 . 50 

Vol.  II.  363  pages,  illustrated $2.50 

British    Standard    Sections.     Issued    by    the    Engineering 

Standards  Committee,  Supported  by  The  Institution  of  Civil 
Engineers,  The  Institution  of  Mechanical  Engineers,  The  Institu- 
tion of  Naval  Architects,  The  Iron  and  Steel  Institute,  and  The 
Institution  of  Electrical  Engineers.  Comprising  9  plates  of 
diagrams,  with  letter-press  and  tables.  Oblong  pamphlet, 
8fXl5 $1.00 

BROWN,  WM.  N.     The  Art  of  Enamelling  on  Metal.  With 
figures  and  illustrations.     12mo,  cloth,  illustrated net,  $1 . 00 

Handbook  on  Japanning  and  Enamelling,  for  Cycles, 

Bedsteads,  Tinware,  etc.     12mo,  cloth,  illustrated net,  $1 . 50 

• House    Decorating    and    Painting.     With    Numerous 

illustrations.     12mo,  cloth net,  $1 .  £0 

History  of  Decorative  Art.     With  Designs  and  Illus- 
trations.    12mo,  cloth net,  $1 . 25 


SCIENTIFIC  PUBLICATIONS.  9 

BROWN,    WM.  N.     Principle    and    Practice    of    Dipping, 

Burnishing,  Lacquering  and  Bronzing  Brass  Ware.     12mo,  cloth. 

ne£,  $1.00 

Workshop  Wrinkles  for  Decorators,  Painters,  Paper- 
Hangers  and  Others.     8vo,  cloth net,  $1 . 00 

BUCHANAN,  E.  E.     Tables  of  Squares.     Containing  the 

square  of  every  foot,  inch,  and  sixteenth  of  an  inch,  between  one 
sixteenth  of  an  inch  and  fifty  feet.  For  Engineers  and  Calcu- 
lators. 16mo,  oblong,  cloth $1 . 00 

BULMAN,   H.   F.,  and   REDMAYNE,   R,  S.   A.     Colliery 

Working  and  Management;  comprising  the  duties  of  a  colliery 
manager,  the  superintendence  and  arrangement  of  labor  and 
wages,  and  the  different  systems  of  working  coal-seams.  With 
engravings,  diagrams,  and  tables.  Second  Edition,  revised  and 
enlarged.  8vo,  cloth,  illustrated net,  $6.00 

BURGH,  N.  P.     Modern  Marine  Engineering,  Applied  to 

Paddle  and  Screw  Propulsion.  Consisting  of  36  colored  plates, 
259  practical  woodcut  illustrations  and  403  pages  of  descriptive 
matter.  The  whole  being  an  exposition  of  the  present  practice 
of  James  Watt  &  Co.,  J.  &  G.  Rennie,  R.  Napier  &  Sons,  and 
other  celebrated  firms.  Thick  quarto,  half  morocco $10 . 00 

BURT,  W.  A.     Key  to  the  Solar  Compass,  and  Surveyor's 

Companion.  Comprising  all  the  rules  necessary  for  use  in  the 
field;  also  description  of  the  Linear  Surveys  and  Public  Land 
System  of  the  United  States,  Notes  on  the  Barometer,  Sugges- 
tions for  an  Outfit  for  a  Survey  of  Four  Months,  etc.  Seventh 
Edition.  Pocket  size,  full  leather $2. 50 

BUSKETT,    E.    W.     Fire   Assaying.     I2mo,    cloth,    illus- 
trated  In  Press. 

CAIN,   W.,   Prof.     Brief   Course   in   the   Calculus.     With 

figures  and  diagrams.     8vo,  cloth,  illustrated net,  $1 .75 

Theory    of    Steel-concrete    Arches    and    of    Vaulted 

Structures.  New  Edition,  revised  and  enlarged.  16mo,  cloth,  il- 
lustrated. (Van  Nostrand  Science  Series). $0 . 50 

CAMPIN,    F.     On    the    Construction    of    Iron    Roofs.     A 

Theoretical  and  Practical  Treatise,  with  woodcuts  and  plates  of 
roofs  recently  executed.  8vo,  cloth $2 . 00 


10  D.  VAN  NOSTRAND  COMPANY'S 

CARPENTER,  Prof.  R.  C.,  and  DIEDERIGHS,  Prof.  H. 

Internal  Combustion  Motors.  With  figures  and  diagrams.  8vo. 
cloth,  illustrated In  Press j 

CARTER,  E.  T.  Motive  Power  and  Gearing  for  Elec- 
trical Machinery.  A  treatise  on  the  Theory  and  Practice  of  the 
Mechanical  Equipment  of  Power  Stations  for  Electrical  Supply 
and  for  Electric  Traction.  Second  Edition,  revised  in  part  by  G. 
Thomas-Da  vies.  8vo,  cloth,  illustrated $5.00 

CATHCART,   WM.   L.,   Prof.     Machine   Design.     Part   I. 

Fastenings.    8vo,  cloth,  illustrated net,  $3 .00 

Machine  Elements ;    Shrinkage  and  Pressure  Joints. 

With  tables  and  diagrams In  Press. 

Marine-Engine  Design In  Press. 

and  CHAFFEE,  J.  I.     Course  of  Graphic  Statics  Applied 

to  Mechanical  Engineering In  Press 

CHAMBER'S    MATHEMATICAL    TABLES,   consisting   of 

Logarithms  of  Numbers  1  to  108,000,  Trigonometrical,  Nautical 
and  other  Tables.  New  Edition.  8vo,  cloth $1 . 75 

CHARPENTIER,    P.     Timber.    A    Comprehensive    Study 

of  Wood  in  all  its  Aspects,  Commercial  and  Botanical.  Show- 
ing the  Different  Applications  and  Uses  of  Timber  in  Various 
Trades,  etc.  Translated  into  English.  8vo,  cloth,  illus. . .  net,  $6 . 00 

CHAUVENET,    W.,    Prof.     New    Method    of    Correcting 

Lunar  Distances,  and  Improved  Method  of  Finding  the  Error 
and  Rate  of  a  Chronometer,  by  Equal  Altitudes.  8vo,  cloth.  $2 . 00 

CHILD,    C.    T.    The   How   and   Why   of   Electricity.    A 

Book  of  Information  for  non-technical  readers,  treating  of  the 
Properties  of  Electricity,  and  how  it  is  generated,  handled,  con- 
trolled, measured  and  set  to  work.  Also  explaining  the  opera- 
tion of  Electrical  Apparatus.  8vo,  cloth,  illustrated $1 . 00 

CHRISTIE,  W.  W.  Boiler-waters,  Scale,  Corrosion,  Foam- 
ing. 8vo,  cloth,  illustrated net,  $3 . 00 

Chimney  Design  and  Theory.     A  Book  for  Engineers 

and  Architects,  with  numerous  half-tone  illustrations  and  plates 
of  famous  chimneys.  Second  Edition,  revised.  8vo,  cloth.  $3.00 


SCIENTIFIC  PUBLICATIONS.  11 

CHRISTIE,  W.  W.  Furnace  Draft :  its  Production  by  Me- 
chanical Methods.  A  Handy  Reference  Book,  with  figures  and 
tables.  16mo,  cloth,  illustrated.  (Van Nostrand's  Science  Series). 

$0.50 

CLAPPERTON,   G.     Practical   Paper-making.    A   Manual 

for  Paper-makers  and  Owners  and  Managers  of  Paper  Mills,  to 
which  is  appended  useful  tables,  calculations,  data,  etc.,  with 
illustrations  reproduced  from  micro-photographs.  12mo,  cloth, 
illustrated $2.50 

CLARK,  D.  K.,  C.E.     A  Manual  of  Rules,  Tables  and 

Data  for  Mechanical  Engineers.  Based  on  the  most  recent  inves- 
tigations. Illustrated  with  numerous  diagrams.  1012  pages.  8vo, 
cloth.  Sixth  Edition $5 . 00 

Fuel:    its  Combustion  and  Economy;  consisting  of 

abridgments  of  Treatise  on  the  Combustion  of  Coal.  By  C.  W. 
Williams,  and  the  Economy  of  Fuel,  by  T.  S.  Prideaux.  With 
extensive  additions  in  recent  practice  in  the  Combustion  and 
Economy  of  Fuel,  Coal,  Coke,  Wood,  Peat,  Petroleum,  etc. 
Fourth  Edition.  12mo,  cloth $1 . 50 

The   Mechanical   Engineer's   Pocket-book   of    Tables, 

Formulae,  Rules  and  Data.  A  Handy  Book  of  Reference  for 
Daily  Use  in  Engineering  Practice.  16mo,  morocco.  Fifth 
Edition,  carefully  revised  throughout $3 . 00 

Tramways :  Their  Construction  and  Working.  Em- 
bracing a  comprehensive  history  of  the  system,  with  accounts  of 
the  various  modes  of  traction,  a  description  of  the  varieties  of 
rolling  stock,  and  ample  details  of  Cost  and  Working  Expenses. 
Second  Edition,  rewritten  and  greatly  enlarged,  with  upwards  of  400 
illustrations.  Thick  8vo,  cloth $89.00 

CLARK,  J.  M.  New  System  of  Laying  Out  Railway  Turn- 
outs instantly,  by  inspection  from  tables.  12mo,  cloth. .  .  $1.00 

CLAUSEN-THUE,  W.     The  ABC  Universal  Commercial 

Electric  Telegraphic  Code;  specially  adapted  for  the  use  of 
Financiers,  Merchants,  Ship-owners,  Brokers,  Agents,  etc.  Fourth 

Edition.     8vo,  cloth $5.00 

Fifth  Edition  of  same $7 . 00 

The  A  1   Universal  Commercial  Electric  Telegraphic 

Code.  Over  1240  pages  and  nearly  90,000  variations.  8vo, 
cloth $7.50 


12  D.  VAN  NOSTRAND  COMPANY'S 

CLEEMANN,   T.   M.     The   Railroad   Engineer's   Practice. 

Being  a  Short  but  Complete  Description  of  the  Duties  of  the 
Young  Engineer  in  Preliminary  and  Location  Surveys  and  in 
Construction.  Fourth  Edition,  revised  and  enlarged.  Illustrated. 
12mo,  cloth $1 . 50 

CLEVENGER,  S.  R.  A  Treatise  on  the  Method  of  Gov- 
ernment Surveying  as  prescribed  by  the  U.  S.  Congress  and  Com- 
missioner of  the  General  Land  Office,  with  complete  Mathemati- 
cal, Astronomical,  and  Practical  Instructions  for  the  use  of  the 
United  States  Surveyors  in  the  field.  16mo,  morocco $2. 50 

CLOUTH,   F.     Rubber,   Gutta-Percha,   and  Balata.     First 

English  Translation  with  Additions  and  Emendations  by  the 
Author.  With  numerous  figures,  tables,  diagrams,  and  folding 
plates.  8vo,  cloth,  illustrated net,  $5.00 

COFFIN,  J.  H.  C.,  Prof.  Navigation  and  Nautical  Astron- 
omy. Prepared  for  the  use  of  the  U.  S.  Naval  Academy.  New 
Edition.  Revised  by  Commander  Charles  Belknap.  52  woodcut 
illustrations.  12mo,  cloth net,  $3 . 50 

COLE,  R.  S.,  M.A.     A  Treatise  on  Photographic  Optics. 

Being  an  account  of  the  Principles  of  Optics,  so  far  as  they  apply 
to  photography.  12mo,  cloth,  103  illus.  and  folding  plates.  .$2. 50 

COLLINS,  J.  E.  The  Private  Book  of  Useful  Alloys  and 
Memoranda  for  Goldsmiths,  Jewelers,  etc.  18mo,  cloth SO .  50 

COLLINS,  T.  B.     The  Steam  Turbine,  or  the  New  Engine. 

8vo,  cloth,  illustrated In  Press. 

COOPER,  W.  R.,  M.A.  Primary  Batteries:  Their  Con- 
struction and  Use.  With  numerous  figures  and  diagrams.  8vo, 
cloth,  illustrated net,  $4 . 00 

COPPERTHWAITE,    WM.    C.     Tunnel   Shields,    and   the 

Use  of  Compressed  Air  in  Subaqueous  Works.  With  numerous 
diagrams  and  figures.  4to,  cloth,  illustrated net ,  $9 . 00 

COREY,  H.  T.   Water-supply  Engineering.   Fully  illustrated. 

In  Press. 

CORNWALL,  H.  B.,  Prof.     Manual  of  Blow-pipe  Analysis, 

Qualitative  and  Quantitative.  With  a  Complete  System  of 
Determinative  Mineralogy.  8vo,  cloth,  with  many  illustra- 
tions. .  $2. 50 


SCIENTIFIC  PUBLICATIONS.  13 

COWELL,  W.  B.  Pure  Air,  Ozone  and  Water.  A  Prac- 
tical Treatise  of  their  Utilization  and  Value  in  Oil,  Grease,  Soap. 
Paint,  Glue  and  other  Industries.  With  tables  and  figures. 
12mo,  cloth,  illustrated net,  $2 . 00 

CRAIG,  B.  F.     Weights  and  Measures.     An  Account  of 

the  Decimal  System,  with  Tables  of  Conversion  for  Commercial 
and  Scientific  Uses.  Square  32mo,  limp  cloth 50 

CROCKER,  F.  B.,  Prof.     Electric   Lighting.     A  Practical 

Exposition  of  the  Art.  For  use  of  Engineers,  Students,  and 
others  interested  in  the  Installation  or  Operation  of  Electrical 
Plants.  Vol.  I.  The  Generating  Plant.  New  Edition,  thoroughly 

revised  and  rewritten.     8vo,  cloth,  illustrated $3 .00 

Vol.  II.  Distributing  Systems  and  Lamps.  Fifth  Edition.  8vo, 
cloth,  illustrated $3.00 

and  WHEELER,  S.  S.    The  Management  of  Electrical 

Machinery.  Being  a  thoroughly  revised  and  rewritten  edition  of 
the  authors'  "Practical  Management  of  Dynamos  and  Motors." 
With  a  special  chapter  by  H.  A.  Foster.  12mo,  cloth,  illustrated. 

net,  $1.00 

CROSSKEY,  L.  R.     Elementary  Perspective:   Arranged  to 

meet  the  requirements  of  Architects  and  Draughtsmen,  and  of 
Art  Students  preparing  for  the  elementary  examination  of  the 
Science  and  Art  Department,  South  Kensington.  With  numer- 
ous full-page  plates  and  diagrams.  8vo,  cloth,  illustrated  .  .  $1 .00 

and  THAW,  J.     Advanced  Perspective,  involving  the 

Drawing  of  Objects  when  placed  in  Oblique  Positions,  Shadows 
and  Reflections.  Arranged  to  meet  the  requirements  of  Archi- 
tects, Draughtsmen,  and  Students  preparing  for  the  Perspective 
Examination  of  the  Education  Department.  With  numerous  full- 
page  plates  and  diagrams.  8vo.  cloth,  illustrated $1 . 50 

DAVIES,    E.    H.     Machinery    for    Metalliferous    Mines. 

A  Practical  Treatise  for  Mining  Engineers,  Metallurgists  and 
Managers  of  Mines.  With  upwards  of  400  illustrations.  Second 
Edition,  rewritten  and  enlarged.  8vo,  cloth net,  $8 . 00 

DAVIES,  D.  C.    A  Treatise  on  Metalliferous  Minerals  and 

Mining.  Sixth  Edition,  thoroughly  revised  and  much  enlarged  by  his 
eon.  8vo,  cloth net,  $5.00 

Mining  Machinery In  Press. 

DAVISON,  G.  C.,  Lieut.    Water-tube  Boilers In  Press. 


14  D.  VAN  NOSTRAND  COMPANY'S 

DAY,  C.     The  Indicator  and  its  Diagrams.     With  Chap 

ters  on  Engine  and  Boiler  Testing;  including  a  Table  of  Piston 
Constants  compiled  by  W.  H.  Fowler.  12mo,  cloth.  125  illus- 
trations   $2.00 

DEITE,  Dr.  C.  Manual  of  Soapmaking,  including  medi- 
cated soaps,  stain-removing  soaps,  metal  polishing  soaps,  soap 
powders  and  detergents.  With  a  treatise  on  perfumes  for  scented 
soaps,  and  their  production  and  tests  for  purity  and  strength. 
Edited  from  the  text  of  numerous  experts.  Translated  from  the 
original  by  S.  I.  King,  F.C.S.  With  figures.  4to,  cloth,  illustrated. 

net,  $5.00 

DE  LA  COUX,  H.     The  Industrial  Uses  of  Water.     With 

numerous  tables,  figures,  and  diagrams.  Translated  from  the 
French  and  revised  by  Arthur  Morris.  8vo,  cloth net,  $4 . 50 

DENNY,  G.  A.     Deep-level  Mines  of  the  Rand,  and  their 

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DIETERICH,  K.     Analysis  of  Resins,  Balsams,  and  Gum 

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DIXON,   D.   B.     The   Machinist's   and   Steam   Engineer's 

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DOBLE,  W.  A.     Power  Plant  Construction  on  the  Pacific 

Coast .  ,  .In  Press. 


SCIENTIFIC  PUBLICATIONS.  15 

DODD,  GEO.  Dictionary  of  Manufactures,  Mining,  Ma- 
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The  Hydro-Metallurgy  of  Copper.     Being  an  Account 

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Cyanide  Process  for  the  Extraction  of  Gold  and  its 

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ELIOT,    C.   W.,    and   STORER,   F.   H.    A   Compendious. 

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ELLIOT,    G.   H.,   Maj.     European   Light-house    Systems. 

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EVERETT,    J.    D.      Elementary    Text-book    of    Physics. 

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FISHER,  H.  K.  C.,  and  DARBY,  W.  C.    Students'  Guide 

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FLEISCHMANN,  W.     The  Book  of  the  Dairy.     A  Manual 

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Centenary    of    the    Electrical     Current,     1799-1899. 

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FOLEY,    N.,    and    PRAY,    THOS.,    Jr.     The    Mechanical 

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FOSTER,  H.  A.     Electrical  Engineers'  Pocket-book.     With 

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able tables,  diagrams,  and  figures.  Third  Edition,  revised 
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FOSTER,    J.    G.,    Gen.,    U.S.A.     Submarine    Blasting    in 

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FOSTER,  J.     Treatise  on  the  Evaporation  of  Saccharine, 

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and  Open  Air.  Third  Edition.  Diagrams  and  large  plates. 
8vo,  cloth, $7.50 

FOX,    WM.,    and    THOMAS,    C.    W.,    M.E.     A    Practical 

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FRANCIS,    J.   B.,   C.E.     Lowell   Hydraulic    Experiments. 

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SCIENTIFIC  PUBLICATIONS.  19 

FRASER,  R.  H.,  and  CLARK,  C.  H.     Marine  Engineering. 

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FULLER,  G.  W.     Report  on  the  Investigations  into  the 

Purification  of  the  Ohio  River  Water  at  Louisville,  Kentucky, 
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FURNELL,  J.      Students'  Manual  of  Paints,  Colors,  Oils 

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GARCKE,    E.,    and    FELLS,    J.    M.     Factory    Accounts: 

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of  specimen  rulings.  Fifth  Edition,  revised  and  extended.  8vo, 
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GEIKIE,  J.     Structural  and  Field  Geology,  for  Students  of 

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tone plates.  8vo,  cloth,  illustrated net,  $4.00 

GERBER,  N.     Chemical  and  Physical  Analysis  of  Milk, 

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GESCHWIND,  L.     Manufacture  of  Alum  and  Sulphates, 

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Charles  Salter.  With  tables,  figures  and  diagrams.  8vo,  cloth, 
illustrated net,  $5 . 00 

GIBBS,  W.  E.     Lighting  by  Acetylene,  Generators,  Burners 

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revised.  12mo,  cloth $1 . 50 

GILLMORE,   Q.  A.,   Gen.     Treatise  on  Limes,  Hydraulic 

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GILLMORE,  Q.  A.,  Gen.  Practical  Treatise  on  the  Con- 
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Report   on   Strength   of  the   Building  Stones  in   the 

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GOLDING,   H.   A.     The   Theta-Phi  Diagram.     Practically 

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GOODEVE,    T.    M.     A   Text-book    on    the    Steam-engine. 

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GORE,  G.,  F.R.S.     The  Art  of  Electrolytic  Separation  of 

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GOULD,  E.  S.  The  Arithmetic  of  the  Steam-engine. 
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GRAY,   J.,   B.Sc.     Electrical   Influence   Machines:    Their 

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GREENWOOD,  E.  Classified  Guide  to  Technical  and  Com- 
mercial Books.  Subject  List  of  Principal  British  and  American 
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GRIFFITHS,   A.   B.,   Ph.D.     A  Treatise   on   Manures,   or 

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Dental    Metallurgy.      A    Manual    for    Students    and 

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GROSS,   E.     Hops,   in   their   Botanical,   Agricultural   and 

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and  illustrations.  8vo,  cloth,  illustrated net,  $4 . 50 


SCIENTIFIC  PUBLICATIONS.  21 

GROVER,    F.     Practical    Treatise    on    Modern    Gas    and 

Oil  Engines.     8vo,  cloth,  illustrated net,  $2.0O 

GRUNER,  A.  Power-loom  Weaving  and  Yarn  Number- 
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GURDEN,   R.   L.     Traverse   Tables:    Computed  to   Four- 

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istance.    For  the  use  of  Surveyors  and  Engineers.     New  Edition. 
Folio,  half  morocco $7 . 50 

GUY,    A.    E.     Experiments    on    the    Flexure    of    Beamsr 

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A.  F.      Electric  Light  and  Power:   Giving  the  Result 

of  Practical  Experience  in  Central-station  Work.  8vo,  cloth, 
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HAEDER,  H.,  C.E.     A  Handbook  on  the  Steam-engine. 

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P.  Powles.  Third  English  Edition,  revised.  8vo,  cloth,  illus- 
trated, 458  pages $3 . 00 


HALL,   C.   H.     Chemistry  of  Paints  and  Paint  Vehicles. 

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HALSEY,   F.   A.     Slide-valve   Gears.     An   Explanation   of 

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HAMILTON,    W.    G.     Useful    Information    for    Railway 

Men.     Tenth  Edition,   revised  and  enlarged.     562  pages,  pocket 
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HAMMER,  W.  J.  Radium,  and  Other  Radio-active  Sub- 
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by  the  Ultra-Violet  Light.  Second  Edition.  With  engravings 
and  photographic  plates.  8vo,  cloth,  illustrated,  72  pp...  $1.00 

HANCOCK,  H.  Text-book  of  Mechanics  and  Hydro- 
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HARDY,    E.     Elementary   Principles    of   Graphic    Statics. 

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HARRISON,    W.    B.     The    Mechanics1    Tool-book.     With 

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HART,  J.  W.     External  Plumbing  Work.    A  Treatise  on 

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8vo,  cloth,  illustrated net,  $3 .00 

i 

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SCIENTIFIC  PUBLICATIONS.  23 

HART,  J.   W.     Principles    of    Hot-water   Supply.     With 

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Sanitary   Plumbing    and   Drainage.    With  numerous 

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HASKINS,   C.   H.     The   Galvanometer   and   its   Uses.     A 

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cloth $1 . 50 

HAUFF,  W.  A.     American  Multiplier:   Multiplications  and 

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24  D.  VAN  NOSTRAND  COMPANY'S 

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HERRMANN,    G.     The   Graphical   Statics   of  Mechanism. 

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SCIENTIFIC  PUBLICATIONS.  25 

HERZFELD,  J.,  Dr.     The  Technical  Testing  of  Yarns  and 

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HOFF,  J.  N.     Paint  and  Varnish  Facts  and  Formulas.     A 

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HOFF,  WM.  B.,  Com.,  U.S.N.     The  Avoidance  of  Collisions 

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HUMBER,  W.,  C.E.     A  Handy  Book  for  the  Calculation 

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Dictionary    of   Chemicals   and   Raw   Products    Used 

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SCIENTIFIC  PUBLICATIONS.  27 

HURST,  G.H.,  F.C.S.     Lubricating  Oils,  Fats  and  Greases : 

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INGLE,    H.     Manual    of    Agricultural"  Chemistry.     8vo, 

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gol 
Wi 


SCIENTIFIC  PUBLICATIONS.  29 

JOHNSON,  W.  McA.    "The  Metallurgy  of  Nickel."  In  Press. 

JOHNSTON,  J.  F.  W.,  Prof.,  and  CAMERON,  Sir  Chas. 

Elements  of  Agricultural  Chemistry  and  Geology.  Seventeenth 
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JOYNSON,    F.    H.     The    Metals    Used    in     Construction. 

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Designing    and    Construction    of    Machine     Gearing. 

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KANSAS    CITY    BRIDGE,    THE.     With    an    Account    of 

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Dynamos,  Motors,  Alternators  and  Rotary  Con- 
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KEMPE,   H.   R.     The   Electrical  Engineer's   Pocket-book 

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KENNEDY,  R.     Modern  Engines  and  Power  Generators. 

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SCIENTIFIC  PUBLICATIONS.  31 

KINZBRUNNER,  C.     Alternate  Current  Windings;    Their 

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KIRKALDY,    W.    G.     Illustrations    of    David    Kirkaldy's 

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plates.  4to,  cloth $10 . 00 

KIRKBRIDE,   J.     Engraving  for  Illustration:    Historical 

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KIRKWOOD,   J.   P.     Report   on   the   Filtration   of  River 

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Illustrated  by  30  double-page  engravings.  4to,  cloth  ....  $7.50 

KLEIN,   J.   F.      Design   of    a   High-speed   Steam-engine. 

With  notes,  diagrams,  formulas  and  tables.  Second  Edition, 
revised  and  enlarged.  8vo,  cloth,  illustrated net,  $5 . 00 

KLEINHANS,  F.  B.     Boiler  Construction.     A  Practical  ex- 

Elanation  of   the  best  modern   methods  of   Boiler  Construction, 
•om  the  laying  out  of  sheets  to  the  completed  Boiler.      With 
diagrams  and  full-page  engravings.     8vo,  cloth,  illustrated. .$3.00 

KNIGHT,   A.   M.,   Lieut.-Com.    U.S.N.     Modern   Seaman- 
ship.    Illustrated  with  136  full-page  plates  and  diagrams.     8vo, 

cloth,  illustrated.     Second  Edition,  revised net,  $6.00 

Half  morocco $7 . 50 

KNOTT,  C.  G.,  and  MACKAY,  J.  S.     Practical  Mathematics. 

With  numerous  examples,  figures  and  diagrams.  New  Edition. 
8vo,  cloth,  illustrated $2 . 00 

KOLLER,    T.     The    Utilization    of    Waste    Products.     A 

Treatise  on  the  Rational  Utilization,  Recovery  and  Treatment 
of  Waste  Products  of  all  kinds.  Translated  from  the  German 
second  revised  edition.  With  numerous  diagrams.  8vo,  cloth, 
illustrated net,  $3 . 50 


32  D.  VAN  NOSTRAND  COMPANY'S 

KOLLER,  T.    Cosmetics.    A  Handbook  of  the  Manufacture, 

Employment  and  Testing  of  all  Cosmetic  Materials  and  Cosmetic 
Specialties.  Translated  from  the  German  by  Chas.  Salter.  8vo. 
cloth net,  $2 . 50 

KRAUCH,    C.,    Dr.     Testing    of    Chemical    Reagents    for 

Purity.  Authorized  translation  of  the  Third  Edition,  by  J.  A. 
Williamson  and  L.  W.  Dupre.  With  additions  and  emendations 
by  the  author.  8vo,  cloth net,  $4 . 50 

LAMBERT,   T.     Lead,  and  its  Compounds.    With  tables, 

diagrams  and  folding  plates.     8vo,  cloth net,  $3 . 50 

• Bone     Products     and     Manures.       An     Account     of 

the  most  recent  improvements  in  the  manufacture  of  Fat,  Glue, 
A-nimal  Charcoal,  Size,  Gelatine  and  Manures.  With  plans  and 
diagrams.  8vo,  cloth,  illustrated net,  $3 . 00 

LAMBORN,  L.  L.     Cottonseed  Products :  A  Manual  of  the 

Treatment  of  Cottonseed  for  its  Products  and  Their  Utilization 
in  the  Arts.  With  Tables,  figures,  full-page  plates,  and  a  large 
folding  map.  8vo,  cloth,  illustrated net,  $3.00 

Modern  Soaps,  Candles,  and  Glycerin.     A   practical 

manual  of  modern  methods  of  utilization  of  Fats  and  Oils  in  the 
manufacture  of  Soaps  and  Candles,  and  the  recovery  of  Glycerin. 
8vo,  cloth,  illustrated net,  $7 . 50 

LAMPRECHT,    R.     Recovery   Work    after   Pit   Fires.     A 

description  of  the  principal  methods  pursued,  especially  in  fiery 
mines,  and  of  the  various  appliances  employed,  such  as  respira- 
tory and  rescue  apparatus,  dams,  etc.  With  folding  plates  and 
diagrams.  Translated  from  the  German  by  Charles  Salter.  8vo, 
cloth,  illustrated net,  $4 . 00 

LARRABEE,  C.  S.  Cipher  and  Secret  Letter  and  Tele- 
graphic Code,  with  Hog's  Improvements.  The  most  perfect 
Secret  Code  ever  invented  or  discovered.  Impossible  to  read 
without  the  key.  18mo,  cloth 60 

LASSAR-COHN,  Dr.  An  Introduction  to  Modern  Scien- 
tific Chemistry,  in  the  form  of  popular  lectures  suited  to  University 
Extension  Students  and  general  readers.  Translated  from  the 
author's  corrected  proofs  for  the  second  German  edition,  by 
M.  M.  Pattison  Muir,  M.A.  12mo,  cloth,  illustrated $2.00 


SCIENTIFIC  PUBLICATIONS.  33 

LATTA,  M.  N.     Gas  Engineering  Practice.     With  figures, 

diagrams  and  tables.     8vo,  cloth,  illustrated: in  Press. 

LEASK,  A.  R.     Breakdowns  at  Sea  and  How  to  Repair 

Them.     With  89  illustrations.     Second  Edition.     8vo,  cloth.  $2 . 00 

Triple  and  Quadruple  Expansion  Engines  and  Boilers 

and  their  Management.     With  59  illustrations.     Third  Edition, 
12mo,  cloth $2.00 


Refrigerating  Machinery:  Its  Principles  and  Man- 
agement. With  64  illustrations.  12mo,  cloth $2.00 

LECKY,    S.    T.    S.     "Wrinkles"   in   Practical   Navigation. 

With  130  illustrations.  8vo,  cloth.  Fourteenth  Edition,  revised 
and  enlarged $8 . 00 

LEFEVRE,  L.     Architectural  Pottery:  Bricks,  Tiles,  Pipes, 

Enameled  Terra-Cottas,  Ordinary  and  Incrusted  Quarries,  Stone- 
ware Mosaics,  Faiences  and  Architectural  Stoneware.  With 
tables,  plates  and  950  cuts  and  illustrations.  With  a  preface  by 
M.  J.-C.  Formige.  Translated  from  the  French,  by  K.  H.  Bird, 
M.A.,  and  W.  Moore  Binns.  4to,  cloth,  illustrated net,  $7.50 

LEHNER,  S.  Ink  Manufacture :  including  Writing,  Copy- 
ing, Lithographic,  Marking,  Stamping  and  Laundry  Inks.  Trans- 
lated from  the  fifth  German  edition,  by  Arthur  Morris  and 
Herbert  Robson,  B.Sc.  8vo,  cloth,  illustrated net,  $2. 50 

LEMSTROM,  Dr.  Electricity  in  Agriculture  and  Horticul- 
ture. Illustrated net ,  $1 . 50 

LEVY,  C.  L.  Electric-light  Primer.  A  simple  and  com- 
prehensive digest  of  all  the  most  important  facts  connected  with 
the  running  of  the  dynamo,  and  electric  lights,  with  precautions 
for  safety.  For  the  use  of  persons  whose  duty  it  is  to  look  after 
the  plant.  8vo,  paper 50 

LIVERMORE,  V.  P.,  and  WILLIAMS,  J.     How  to  Become 

a  Competent  Motorman.  Being  a  Practical  Treatise  on  the 
Proper  Method  of  Operating  a  Street  Railway  Motor  Car;  also 
giving  details  how  to  overcome  certain  defects.  16mo,  cloth, 
illustrated,  132  pages $1 .00 


34  D.  VAN  NOSTRAND  COMPANY'S 

LOBBEN,  P.,  M.E.  Machinists'  and  Draftsmen's  Hand- 
book, containing  Tables,  Rules,  and  Formulas,  with  numerous 
examples,  explaining  the  principles  of  mathematics  and  mechanics, 
as  applied  to  the  mechanical  trades.  Intended  as  a  reference  book 
for  all  interested  in  Mechanical  work.  Illustrated  with  many 
cuts  and  diagrams.  Svo,  cloth $2 . 50 

LOCKE,  A.   G.   and  C.   G.     A  Practical    Treatise  on   the 

Manufacture  of  Sulphuric  Acid.  With  77  constructive  plates, 
drawn  to  scale  measurements,  and  other  illustrations.  Royal 
Svo,  cloth $10.00 

LOCKERT,  L.     Petroleum  Motor-cars.     i2mo,  cloth,  $1.50 

LCCKWOOD,  T.  D.  Electricity,  Magnetism,  and  Electro- 
telegraphy.  A  Practical  Guide  for  Students,  Operators,  and 
Inspectors.  Svo,  cloth .  Third  Edition $2 . 50 

Electrical  Measurement  and  the  Galvanometer:    its 

Construction  and  Uses.  Second  Edition.  32  illustrations.  12mo, 
cloth $1 .50 

LODGE,  O.  J.  Elementary  Mechanics,  including  Hydro- 
statics and  Pneumatics.  Revised  Edition.  12mo,  cloth  ...  SI .  50 

Signalling  Across   Space,   Without   Wires:     being   a 

description  of  the  work  of  Hertz  and  his  successors.  With  numer- 
ous diagrams  and  half-tone  cuts,  and  additional  remarks  con- 
cerning the  application  to  Telegraphy  and  later  developments. 
Third  Edition.  Svo,  cloth,  illustrated net,  $2 . 00 

LORD,  R.  T.     Decorative  and  Fancy  Fabrics.     A  Valuable 

Book  with  designs  and  illustrations  for  manufacturers  and  de- 
signers of  Carpets,  Damask,  Dress  and  all  Textile  Fabrics.  Svo, 
cloth,  illustrated net,  $3 . 50 

LORING,   A.   E.     A   Handbook   of   the   Electro-magnetic 

Telegraph.     16mo,  cloth,  boards.     New  and  enlarged  edition.  .    .50 

LUCE,  S.  B.  (Com.,  U.  S.  N.).     Text-book  of  Seamanship. 

The  Equipping  and  Handling  of  Vessels  under  Sail  or  Steam. 
For  the  use  of  the  U.  S.  Naval  Academy.  Revised  and  enlarged 
edition,  by  Lieut.  Wm.  S.  Benson.  Svo,  cloth,  illustrated. $10. 00 

LUCKE,   C.   E.     Gas  Engine   Design.     With  figures  and 

diagrams.     Second  Edition,  revised.     Svo,  cloth,  illustrated. 

ne£,  $3.00 

Power,   Cost  and  Plant  Designs   and   Construction. 

In  Press. 


SCIENTIFIC  PUBLICATIONS.  35 

LUCKE,  C.  E.     Power  Plant  Papers.     Form  I.     The  Steam 

Power  Plant.     Pamphlet  (8X13) net,  $1 .50 

LUNGE,   G.,  Ph.D.      Coal-tar  and  Ammonia:    being  the 

third  and  enlarged  edition  of  "A  Treatise  on  the  Distillation  of 
Coal-tar  and  Ammoniacal  Liquor,"  with  numerous  tables,  figures 
and  diagrams.  Thick  8vo,  cloth,  illustrated net,  $15.00 

A  Theoretical  and  Practical  Treatise  on  the  Man- 
ufacture of  Sulphuric  Acid  and  Alkali  with  the  Collateral  Branches. 

• Vol.  I.  Sulphuric  Acid.   In  two  parts,  not  sold  separately. 

Second  Edition,  revised  and  enlarged.   342  illus.   8vo,  cloth .  .  $1 5 . 00 

Vol.  II.   Salt  Cake,  Hydrochloric   Acid  and  Leblanc 

Soda.     Second  Edition,  revised  and  enlarged.     8vo,  cloth .  .  .  $15 . 00 

Vol.  III.    Ammonia  Soda,  and  various  other  processes 

of  Alkali-making,  and  the  preparation  of  Alkalis,  Chlorine  and 
Chlorates,  by  Electrolysis.  8vo,  cloth.  New  Edition,  1896 .  .  $15 . 00 

and  HURTER,  F.      The  Alkali  Maker's  Handbook. 

Tables  and  Analytical  Methods  for  Manufacturers  of  Sulphuric 
Acid,  Nitric  Acid,  Soda,  Potash  and  Ammonia.  Second  Edition. 
12mo,  cloth $3 . 00 

LUPTON,  A.,  PARR,  G.  D.  A.,  and  PERKIN,  H.  Elec- 
tricity as  Applied  to  Mining.  With  tables,  diagrams  and  folding 
plates.  Second  Edition,  reprised  and  enlarged.  8vo,  cloth,  illus- 
trated  net,  $4.50 

LUQUER,   L.   M.,  Ph.D.  (Columbia  Univ.).     Minerals  in 

Rock  Sections.  The  Practical  Method  of  Identifying  Minerals  in 
Rock  Sections  with  the  Microscope.  Especially  arranged  for 
Students  in  Technical  and  Scientific  Schools.  Revised  Edition. 
8vo,  cloth,  illustrated net,  $1 . 50 

MACKIE,    JOHN.     How   to   Make    a   Woolen   Mill   Pay. 

8vo,  cloth net,  $2 . 00 

MACKROW,  C.     The  Naval  Architect's  and  Ship-builder's 

Pocket-book  of  Formulae,  Rules,  and  Tables;  and  Engineers'  and 
Surveyors'  Handy  Book  of  Reference.  Eighth  Edition,  revised 
and  enlarged.  16mo,  limp  leather,  illustrated $5,00 

MAGUIRE,   E.,    Capt.,   U.S.A.     The   Attack   and  Defence 

of  Coast  Fortifications  With  maps  and  numerous  illustrations, 
8vo,  cloth $2 . 50 


36  D.  VAN  NOSTRAND  COMPANY'S 

MAGUIRE,    WM.    R.     Domestic    Sanitary    Drainage    and 

Plumbing  Lectures  on  Practical  Sanitation.  332  illustrations. 
8vo . .. $4.00 

MAILLOUX,    C.    0.      Electro-traction    Machinery.      8vo, 
cloth,  illustrated In  Press. 

MARKS,  E.   C.   R.     Notes  on  the  Construction  of  Cranes 

and  Lifting  Machinery.  With  numerous  diagrams  and  figures. 
New  and  enlarged  edition.  12mo,  cloth net,  $1 . 50 

Notes  on  the  Construction  and  Working  of  Pumps. 

With  figures,  diagrams  and  engravings.  12mo,  cloth,  illus- 
trated  net,  $1 . 50 

G.  C.     Hydraulic    Power    Engineering.     A  Practical 

Manual  on  the  Concentration  and  Transmission  of  Power  by  Hy- 
draulic Machinery.  With  over  200  diagrams  and  tables  8vo, 
«loth,  illustrated $3 . 50 


MARSH,  C.  F.     Reinforced  Concrete.     With  full-page  and 

folding  plates,  and  512  figures  and  diagrams.     4to,  cloth,  illus- 
trated  net,  $7.00 


MAVER,  W.     American  Telegraphy:    Systems,  Apparatus, 
Operation.     450  illustrations.     8vo,  cloth $5 . 00 

MAYER,  A.  M.,  Prof.     Lecture  Notes  on  Physics.     8vo, 
cloth $2.00 

McCULLOCH,  R.  S.,  Prof.     Elementary  Treatise  on  the 

Mechanical  Theory  of  Heat,  and  its  application  to  Air  and  Steam- 
engines.  8vo,  cloth $3 . 50 

McINTOSH,  J.  G.   Technology  of  Sugar.   A  Practical  Treatise 

on  the  Manufacture  of  Sugar  from  the  Sugar-cane  and  Sugar- 
beet.  With  diagrams  and  tables.  8vo,  cloth,  illustrated .  net,  $4 . 50 

• Manufacture   of  Varnishes   and   Kindred  Industries. 

Based  on  and  including  the  "  Drying  Oils  and  Varnishes,"  of 
Ach.  Livache.  Volume  I.  Oil  Crushing,  Refining  and  Boiling, 
Manufacture  of  Linoleum,  Printing  and  Lithographic  Inks,  and 
India-rubber  Substitutes.  Second  greatly  enlarged  English  Edi- 
tion. 8vo,  cloth,  illustrated net,  $3.50 

-  (To  be  complete  in  three  volumes.) 


SCIENTIFIC  PUBLICATIONS.  37 

McNEILL,    B.     McNeilPs    Code.     Arranged    to    meet    the 

requirements  of  Mining,  Metallurgical  and  Civil  Engineers,  Direc- 
tors of  Mining,  Smelting  and  other  Companies,  Bankers,  Stock 
and  Share  Brokers,  Solicitors,  Accountants,  Financiers  and 
General  Merchants.  Safety  and  Secrecy.  8vo,  cloth.  ...  $6 . 00 

McPHERSON,    J.    A.,    A.    M.    Inst.    C.    E.     Waterworks 

Distribution.  A  practical  guide  to  the  laying  out  of  systems  of 
distributing  mains  for  the  supply  of  water  to  cities  and  towns 
With  tables,  folding  plates  and  numerous  full-page  diagrams 
8vo,  cloth,  illustrated $2 . 50 

MERCK,  E.     Chemical  Reagents:  Their  Purity  and  Tests. 

In  Press. 

MERRITT,  WM.  H.     Field  Testing  for  Gold  and  Silver. 

A  Practical  Manual  for  Prospectors  and  Miners.  With  numerous 
half-tone  cuts,  figures  and  tables.  16mo,  limp  leather,  illus- 
trated   $1 .50 

METAL  TURNING.  By  a  Foreman  Pattern-maker.  Illus- 
trated with  81  engravings.  12mo,  cloth $1 . 50 

MICHELL,  S.  Mine  Drainage:  being  a  Complete  Prac- 
tical Treatise  on  Direct-acting  Underground  Steam  Pumping 
Machinery.  Containing  many  folding  plates,  diagrams  and 
tables.  Second  Edition,  rewritten  and  enlarged.  Thick  8vo, 
cloth,  illustrated $10.00 

MIERZINSKI,  S.,  Dr.  Waterproofing  of  Fabrics.  Trans- 
lated from  the  German  by  Arthur  Morris  and  Herbert  Robson. 
With  diagrams  and  figures.  8vo,  cloth,  illustrated...  net,  $2.50 

MILLER,  E.  H.  (Columbia  Univ.).     Quantitative  Analysis 

for  Mining  Engineers.    8vo,  cloth net,  $1 . 50 

MINIFIE,    W.     Mechanical    Drawing.     A    Text-book    of 

Geometrical  Drawing  for  the  use  of  Mechanics  and  Schools,  in 
which  the  Definitions  and  Rules  of  Geometry  are  familiarly  ex- 
plained; the  Practical  Problems  are  arranged  from  the  most 
simple  to  the  more  complex,  and  in  their  description  technicalities 
are  avoided  as  much  as  possible.  With  illustrations  for  drawing 
Plans,  Sections,  and  Elevations  of  Railways  and  Machinery;  an 
Introduction  to  Isometrical  Drawing,  and  an  Essay  on  Linear 
Perspective  and  Shadows.  Illustrated  with  over  200  diagrams 
engraved  on  steel.  Tenth  Thousand,  revised.  With  an  Appen- 
dix on  the  Theory  and  Application  of  Colors.  8vo,  cloth .  .  $4 . 00 


38  D.  VAN  NOSTRAND  COMPANY'S 

MINIFIE,  W-     Geometrical  Drawing.      Abridged  from  the 

octavo  edition,  for  the  use  of  schools.  Illustrated  with  48  steel 
plates.  Ninth  Edition.  12mo,  cloth $2 . 00 

MODERN   METEOROLOGY.      A   Series    of   Six   Lectures, 

delivered  under  the  auspices  of  the  Meteorological  Society  in 
1870.  Illustrated.  12mo,  cloth $1 .50 

MOORE,  E.  C.  S.  New  Tables  for  the  Complete  Solu- 
tion of  Ganguillet  and  Kutter's  Formula  for  the  flow  of  liquids  in 
open  channels,  pipes,  sewers  and  conduits.  In  two  parts.  Part  I, 
arranged  for  1080  inclinations  from  1  over  1  to  1  over  21,120  for 
fifteen  different  values  of  (n).  Part  II,  for  use  with  all  other 
values  of  (n).  With  large  folding  diagram.  Svo,  cloth,  illus- 
trated  net,  $5 . 00 

MOREING,  C.  A.,  and  NEAL,  T.     New  General  and  Mining 

Telegraph  Code.  676  pages,  alphabetically  arranged.  For  the 
use  of  mining  companies,  mining  engineers,  stock  brokers,  financial 
agents,  and  trust  and  finance  companies.  Eighth  Edition.  Svo, 
cloth $5 . 00 

MOSES,  A.  J.  The  Characters  of  Crystals.  An  Intro- 
duction to  Physical  Crystallography,  containing  321  illustrations 
and  diagrams.  Svo net,  $2 . 00 

and    PARSONS,    C.    L.     Elements    of    Mineralogy, 

Crystallography  and  Blowpipe  Analysis  from  a  Practical  Stand- 
point. Third  Enlarged  Edition.  Svo,  cloth,  336  illustrations, 

net,  $2.50 

MOSS,  S.  A.     Elements  of  Gas  Engine  Design.    Reprint 

of  a  Set  of  Notes  accompanying  a  Course  of  Lectures  delivered 
at  Cornell  University  in  1902.  16mo,  cloth,  illustrated.  (Van 
Nostrand's  Science  Series) $0.50 

MOSS,  S.  A.     The  Lay-out  of  Corliss  Valve  Gears.     (Van 

Nostrand's  Science  Series.)     16mo,  cloth,  illustrated $0.50 

MULLIN,  J.  P.,  M.E.  Modern  Moulding  and  Pattern- 
making.  A  Practical  Treatise  upon  Pattern-shop  and  Foundry 
Work:  embracing  the  Moulding  of  Pulleys,  Spur  Gears,  Worm 
Gears,  Balance-wheels,  Stationary  Engine  and  Locomotive 
Cylinders,  Globe  Valves,  Tool  Work,  Mining  Machinery,  Screw 
Propellers,  Pattern-shop  Machinery,  and  the  latest  improve- 
ments in  English  and  American  Cupolas;  together  with  a  large 
collection  of  original  and  carefully  selected  Rules  and  Tables 
for  every-day  use  in  the  Drawing  Office,  Pattern-shop  and  Foundry.- 
12mo,  cloth,  illustrated $2.50 


SCIENTIFIC  PUBLICATIONS.  39 

MUNRO,  J.,  C.E.,  and  JAMIESON,  A.,  C.E.  A  Pocket- 
book  of  Electrical  Rules  and  Tables  for  the  use  of  Electricians 
and  Engineers.  Fifteenth  Edition,  revised  and  enlarged.  With 
numerous  diagrams.  Pocket  size.  Leather $2 . 50 

MURPHY,  J.  G.,  M.E.     Practical  Mining.     A  Field  Manual 

for  Mining  Engineers.  With  Hints  for  Investors  in  Mining 
Properties.  16mo,  cloth $1 . 00 

NAQUET,  A.     Legal  Chemistry.     A  Guide  to  the  Detection 

of  Poisons,  Falsification  of  Writings,  Adulteration  of  Alimentary 
and  Pharmaceutical  Substances,  Analysis  of  Ashes,  and  Exami- 
nation of  Hair,  Coins,  Arms  and  Stains,  as  applied  to  Chemical 
Jurisprudence,  for  the  use  of  Chemists,  Physicians,  Lawyers, 
Pharmacists  and  Experts.  Translated,  with  additions,  including 
a  list  of  books  and  memoirs  on  Toxicology,  etc.,  from  the  French, 
by  J.  P.  Battershall,  Ph.D.,  with  a  Preface  by  C.  F.  Chandler, 
Ph.D.,  M.D.,  LL.D.  12mo,  cloth $2.00 

NASMITH,    J.     The    Student's    Cotton    Spinning.     Third 

Edition,  revised  and  enlarged.  Svo,  cloth,  622  pages,  250  illus- 
trations   $3 . 00 

NEUBURGER,    H.,    and   NOALHAT,   H.     Technology   of 

Petroleum.  The  Oil  Fields  of  the  World:  their  History,  Geog- 
raphy and  Geology.  Annual  Production,  Prospection  and  Develop- 
ment; Oil-well  Drilling;  Transportation  of  Petroleum  by  Land 
and  Sea.  Storage  of  Petroleum.  With  153  illustrations  and  25 
plates.  Translated  from  the  French,  by  John  Geddes  Mclntosh. 
Svo,  cloth,  illustrated net,  $10.00 

NEW  ALL,  J.  W.     Plain  Practical  Directions  for  Drawing, 

Sizing  and  Cutting  Bevel-gears,  showing  how  the  Teeth  may 
be  cut  in  a  Plain  Milling  Machine  or  Gear  Cutter  so  as  to  give 
them  a  correct  shape  from  end  to  end;  and  showing  how  to  get 
out  all  particulars  for  the  Workshop  without  making  any  Draw- 
ings. Including  a  Full  Set  of  Tables  of  Reference.  Folding 
plates.  Svo,  cloth $1 . 50 

NEWLANDS,  J.     The  Carpenters'  and  Joiners'  Assistant: 

being  a  Comprehensive  Treatise  on  the  Selection,  Preparation 
and  Strength  of  Materials,  and  the  Mechanical  Principles  of 
Framing,  with  their  application  in  Carpentry,  Joinery  and 
Hand-railing;  also,  a  Complete  Treatise  on  Sines;  and  an  Illus- 
trated Glossary  of  Terms  used  in  Architecture  and  Building. 
Illustrated.  Folio,  half  morocco $15.00 


40  D.  VAN  NOSTRAND  COMPANY'S 

NIPHER,  F.  E.,  A.M.     Theory  of  Magnetic  Measurements, 

with  an  Appendix  on  the  Method  of  Least  Squares.  12mo, 
cloth $1 . 00 

NOLL,  AUGUSTUS.     How  to  Wire  Buildings:    A  Manual 

of  the  Art  of  Interior  Wiring.  With  many  illustrations.  Fourth 
Edition.  8vo,  cloth,  illustrated $1 . 50 

NUGENT,   E.     Treatise   on   Optics;    or,   Light   and   Sight 

Theoretically  and  Practically  Treated,  with  the  Application  to 
Fine  Art  and  Industrial  Pursuits.  With  103  illustrations.  12mo, 
cloth $1 . 50 

O'CONNOR,  H.  The  Gas  Engineer's  Pocket-book.  Com- 
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facture, Distribution  and  Use  of  Coal-gas  and  the  Construction 
of  Gas-works.  Second  Edition,  revised.  12mo,  full  leather,  gilt 
edges $3 . 50 

OLSEN,  J.  C.,  Prof.  Text-book  of  Quantitative  Chemical 
Analysis  by  Gravimetric,  Electrolytic,  Volumetric  and  Gasometric 
Methods.  With  Seventy-two  Laboratory  Exercises  giving  the 
Analysis  of  Pure  Salts,  Alloys,  Minerals  and  Technical  Products. 
With  numerous  figures  and  diagrams.  Second  Edition,  revised. 
8vo,  cloth net,  $4.00 

OSBORN,  F.  C.     Tables  of  Moments  of  Inertia,  and  Squares 

of  Radii  of  Gyration;  supplemented  by  others  on  the  Ultimate 
and  Safe  Strength  of  Wrought-iron  Columns,  Safe  Strength  of 
Timber  Beams,  and  Constants  for  readily  obtaining  the  Shearing 
Stresses,  Reactions  and  Bending  Moments  in  Swing  Bridges. 
Fifth  Edition,  12mo,  leather net,  $3.00 

OUDIN,  M.  A.     Standard  Polyphase  Apparatus  and  Systems. 

With  many  diagrams  and  figures.  Third  Edition,  thoroughly 
revised.  Fully  illustrated $3 . 00 

PALAZ,  A.,  Sc.D.     A  Treatise  on  Industrial  Photometry, 

with  special  application  to  Electric  Lighting.  Authorized  trans- 
lation from  the  French  by  George  W.  Patterson,  Jr.  Second 
Edition,  revised.  8vo,  cloth,  illustrated $4.00 

PAMELY,  C.  Colliery  Manager's  Handbook.  A  Compre- 
hensive treatise  on  the  Laying-out  and  Working  of  Collieries. 
Designed  as  a  book  of  reference  for  colliery  managers  and  for  the 
use  of  coal-mining  students  preparing  for  first-class  certificates. 
Fifth  Edition,  revised  and  enlarged.  Containing  over  1,000  dia- 
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SCIENTIFIC  PUBLICATIONS.  41 

PARR,  G.  D.  A.  Electrical  Engineering  Measuring  Instru- 
ments, for  Commercial  and  Laboratory  Purposes.  With  370 
diagrams  and  engravings.  8vo,  cloth,  illustrated net,  S3 . 50 

PARRY,  E.  J.,  B.Sc.      The  Chemistry  of  Essential  Oils 

and  Artificial  Perfumes.  Being  an  attempt  to  group  together 
the  more  important  of  the  published  facts  connected  with  the 
subject;  also  giving  an  outline  of  the  principles  involved  in  the 
preparation  and  analysis  of  Essential  Oils.  With  numerous  dia- 
grams and  tables.  8vo,  cloth,  illustrated net,  $5 . 00 

and  COSTE,  J.  H.      Chemistry  of  Pigments.     With 

tables  and  figures.     8vo,  cloth net,  $4 . 50 

PARRY,  L.  A.,  M.D.     The  Risks  and  Dangers  of  Various 

Occupations  and  their  Prevention.  A  book  that  should  be  in 
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and  workmen.  8vo,  cloth net,  $3 . 00 

PARSHALL,    H.    F.,    and  HOBART,    H.    M.      Armature 

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and  PARRY,  E.     Electrical  Equipment  of  Tramways. 

In  Press. 

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jects. 8vo,  cloth net,  $3 . 50 

PATERSON,   D.,   F.C.S.      The   Color  Printing   of   Carpet 

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With  numerous  illustrations.  8vo,  cloth,  illustrated .  .  .  net,  $3 . 50 

Color  Matching  on  Textiles.     A  Manual  intended  for 

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patterns  in  appendix.  8vo,  cloth,  illustrated net,  $3 . 00 


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figures,  tables,  and  colored  plate.  8vo,  cloth,  illustrated .  net,  $3 . 00 

PATTEN,    J.      A   Plan   for   Increasing   the    Humidity   of 

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of  the  United  States  for  Power  and  other  Purposes.  A  paper 
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42  D.  VAN  NOSTRAND  COMPANY'S 

PATTON,    H.    B.      Lecture    Notes    on     Crystallography 

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dents at  the  Colorado  School  of  Mines.  With  blank  pages  for 
note-taking.  8vo,  cloth net  $1 . 25 

PAULDING,  C.  P.  Practical  Laws  and  Data  on  the  Con- 
densation of  Steam  in  Covered  and  Bare  Pipes;  to  which  is  added 
a  translation  of  Pellet's  "Theory  and  Experiments  on  the  Trans- 
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illustrated,  102  pages net,  $2.00 

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Every  Kind.  A  Manual  for  refrigerating  engineers.  With  tables 
and  diagrams.  12mo,  cloth,  illustrated net,  $1 .00 

PEIRCE,     B.       System     of    Analytic     Mechanics.       4to, 

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PERRINE,  F.  A.  C.,  A.M.,  D.Sc.  Conductors  for  Elec- 
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and  other  Uses.  With  numerous  diagrams  and  engravings.  8vo, 
cloth,  illustrated,  287  pages net ,  $3 . 50 

PERRY,  J.      Applied  Mechanics.     A  Treatise  for  the  Use 

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PHILLIPS,     J.       Engineering     Chemistry.      A     Practical 

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Engineering  works,  with  numerous  Analyses,  Examples,  and 
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8vo,  cloth net,  $4 . 50 

Gold  Assaying.      A  Practical  Handbook  giving  the 

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and  engravings.  8vo,  cloth,  illustrated net,  $2 . 50 

PHIN,  J.     Seven  Follies  of  Science.     A  Popular  Account 

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which  have  been  made  to  solve  them;  to  which  is  added  a  small 
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numerous  illustrations.  8vo,  cloth,  illustrated net,  $1 .25 


SCIENTIFIC  PUBLICATIONS.  43 

PICKWORTH,  C.  N.  The  Indicator  Handbook.  A  Prac- 
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struction and  Application.  81  illustrations.  12mo,  cloth.  $1.50 

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Logarithms  for  Beginners.     8vo,  boards $0.50 

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with  Numerous  Rules  and  Practical  Illustrations,  exhibiting  the 
Application  of  the  Instrument  to  the  Every-day  Work  of  the 
Engineer — Civil,  Mechanical  and  Electrical.  Seventh  Edition. 
12mo,  flexible  cloth $1 . 00 

Plane  Table,  The.  Its  Uses  in  Topographical  Survey- 
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Illustrated.     8vo,  cloth.  . $2.00 

"This  work  gives  a  description  of  the  Plane  Table  employed  at 
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PLATTNER'S   Manual    of    Qualitative    and    Quantitative 

Analysis  with  the  Blow-pipe.  Eighth  Edition,  revised.  Translated 
by  Henry  B.  Cornwall,  E.M.,  Ph.D.,  assisted  by  John  H.  Caswell, 
A.M.  From  the  sixth  German  edition,  by  Prof.  Friederich  Kol- 
beck.  With  87  woodcuts.  463  pages.  8vo,  cloth net,  $4.00 

PLYMPTON,   GEO.   W.,  Prof.      The  Aneroid  Barometer: 

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trated   $0.50 

POCKET   LOGARITHMS,    to    Four   Places   of   Decimals, 

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POPE,  F.  L.     Modern  Practice  of  the  Electric  Telegraph. 

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cloth $1.50 

POPPLEWELL,  W.  C.     Elementary  Treatise  on  Heat  and 

Heat  Engines.  Specially  adapted  for  engineers  and  students  of 
engineering.  12mo,  cloth,  illustrated $3.00 


44  D.  VAN  NOSTRAND  COMPANY'S 

POPPLEWELL,  W.  C.     Prevention   of  Smoke,   combined 

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Practical   Iron   Founding.     By   the    Author   of    "  Pattern 

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PRAY,  T.,  Jr.     Twenty  Years  with  the  Indicator:    being 

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complex  Formulae.  Illustrated.  8vo,  cloth $2.5^ 

Steam  Tables  and  Engine  Constant.     Compiled  from 

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PREECE,  W.  H.     Electric  Lamps In  Press. 

and  STUBBS,  A.  T.      Manual  of  Telephony.     Illus- 
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PRELINI,  C.,  C.E.    Earth  and  Rock  Excavation.    A  Manual 

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net,  $3.00 

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Second  Edition,  revised.  8vo,  cloth,  illustrated $3.00 

PREMIER  CODE.     (See  Hawke,  Wm.  H.) 

PRESCOTT,  A.   B.,   Prof.     Organic  Analysis.     A  Manual 

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SCIENTIFIC  PUBLICATIONS.  45 

PRESCOTT,  A.  B.,  Prof.     Outlines  of  Proximate  Organic 

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pounds. Fourth  Edition.  12mo,  cloth $1 . 75 

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8vo,  cloth net,  $3 . 50 

and  SULLIVAN,  E.  C.  (University  of  Michigan).    First 

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cloth net,  $1 . 50 

PRITCHARD,  0.  G.      The   Manufacture   of  Electric-light 

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PROST,  E.     Manual  of  Chemical  Analysis  as  Applied  to 

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PULLEN,   W.   W.   F.      Application   of   Graphic  Methods 

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PYNCHON,  T.  R.,  Prof.     Introduction  to  Chemical  Physics, 

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46  D.  VAN  NOSTRAND  COMPANY'S 

RADFORD,  C.  S.,  Lieut.      Handbook  on  Naval  Gunnery. 

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Tables  for  Sewerage  and  Hydraulic  Engineers,  In  Press. 

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cloth $6 . 00 

RAM,  G.  S.  The  Incandescent  Lamp  and  its  Manufac- 
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RAMP,  H.  M.     Foundry  Practice In  Press. 

RANDALL,  J.  E.  A  Practical  Treatise  on  the  Incan- 
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RANDALL,    P.    M.     Quartz    Operator's   Handbook.     New 

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RANDAU,  P.     Enamels  and  Enamelling.    An  introduction 

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technical  and  artistic  purposes.  For  enamel-makers,  workers 
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RANKINE,    W.    J.    M.     Applied   Mechanics.     Comprising 

the  Principles  of  Statics  and  Cinematics,  and  Theory  of  Struc- 
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Civil  Engineering.  Comprising  Engineering  Sur- 
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SCIENTIFIC  PUBLICATIONS.  47 

RANKINE,  W.  J.  M.  Machinery  and  Millwork.  Compris- 
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$5.00 

The  Steam-engine   and  Other  Prime  Movers.     With 

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numerous  tables  and  illustrations.  Fifteenth  Edition,  thor- 
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Useful   Rules  and  Tables  for  Engineers  and  Others. 

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and  BAMBER,  E.  F.,  C.E.     A  Mechanical  Text-book. 

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RAPHAEL,    F.    C.     Localization    of    Faults    in    Electric 

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RAYMOND,  E.  B.  Alternating-current  Engineering  Prac- 
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RAYNER,  H.     Silk  Throwing    and  Waste  Silk  Spinning. 

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RECIPES    for  the  Color,  Paint,  Varnish,   Oil,  Soap  and 

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cloth $3.50 


48  D.  VAN  NOSTRAND  COMPANY'S 

RECIPES  FOR    FLINT  GLASS  MAKING.     Being  Leaves 

from  the  mixing-book  of  several  experts  in  the  Flint  Glass  Trade. 
Containing  up-to-date  recipes  and  valuable  information  as  to 
Crystal,  Demi-crystal,  and  Colored  Glass  in  its  many  varieties. 
It  contains  the  recipes  for  cheap  metal  suited  to  pressing,  blowing, 
etc.,  as  well  as  the  most  costly  Crystal  and  Ruby.  British  manu- 
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time.  The  book  also  contains  remarks  as  to  the  result  of  the 
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REED'S   ENGINEERS'  HANDBOOK  to  the  Local  Marine 

Board  Examinations  for  Certificates  of  Competency  as  First  and 
Second  Class  Engineers.  By  W.  H.  Thorn.  With  the  answers 
to  the  Elementary  Questions.  Illustrated  by  358  diagrams 
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8vo,  cloth $5 . 00 

Key  to  the  Seventeenth  Edition  of  Reed's  Engineers' 

Handbook  to  the  Board  of  Trade  Examination  for  First  and 
Second  Class  Engineers,  and  containing  the  workings  of  all  the 
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SCIENTIFIC  PUBLICATIONS.  49 

REISER,  N.     Faults  in  the  Manufacture  of  Woolen  Goods, 

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50  D.  VAN  NOSTRAND  COMPANY'S 

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SCIENTIFIC  PUBLICATIONS.  51 

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SEATON,  A.  E.     A  Manual  of  Marine  Engineering.     Com- 

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and    ROUNTHWAITE,    H.    M.      A   Pocket-book   of 

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SEIDELL,    A.     Handbook    of    Solubilities.     i2mo,  cloth. 

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SEWALL,   C.   H.     Wireless  Telegraphy.     With    diagrams 

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SCIENTIFIC  PUBLICATIONS.  53 

SHAW,  S.     The  History  of  the  Staffordshire  Potteries,  and 

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SHELDON,  S.,  Ph.D.,  and  MASON,  H.,  B.S.  Dynamo- 
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Alternating-current     Machines:     being     the     second 

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SHIELDS,    J.    E.     Notes    on    Engineering    Construction. 

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SHOCK,  W.  H.  Steam  Boilers:  their  Design,  Construc- 
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SHREVE,  S    H.     A  Treatise  on  the  Strength  of  Bridges 

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SHUNK,   W.    F.     The    Field   Engineer.     A   Handy   Book 

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SIMMS,  F.  W.     A  Treatise  on  the  Principles  and  Practice 

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SIMPSON,   G.     The  Naval  Constructor.     A  Vade  Mecum 

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SLATER,    J.    W.     Sewage     Treatment,    Purification    and 

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SCIENTIFIC  PUBLICATIONS.  55 

SOXHLET,   D.  H.     Art   of  Dyeing  and  Staining  Marble, 

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SPANG,  H.  W.  A  Practical  Treatise  on  Lightning  Pro- 
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SPEYERS,     C.     L.     Text-book     of    Physical     Chemistry. 

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56  D.  VAN  NOSTRAND  COMPANY'S 

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STONEY,  B.  D.     The  Theory  of  Stresses  in  Girders  and 

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SUFFLING,  E.  R.     Treatise  on  the  Art  of  Glass  Painting. 

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SWOOPE,  C.  W.  Practical  Lessons  in  Electricity:  Prin- 
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TAILFER,    L.     Practical    Treatise    on    the    Bleaching    of 

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TEMPLETON,  W.      The  Practical  Mechanic's  Workshop 

Companion.  Comprising  a  great  variety  of  the  most  useful 
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SCIENTIFIC  PUBLICATIONS.  57 

THOM,  C.,  and  JONES,  W.  H.     Telegraphic  Connections: 

embracing  Recent  Methods  in  Quadruplex  Telegraphy.     20  full- 
page  plates,  some  colored.     Oblong,  8vo,  cloth $1 .50 


THOMAS,  C.  W.     Paper-makers'  Handbook.    A  Practical 

Treatise.     Illustrated.  .  ..In  Press. 


THOMPSON,  A.  B.     Oil  Fields  of  Russia  and  the  Russian 

Petroleum  Industry.  A  Practical  Handbook  on  the  Explora- 
tion, Exploitation,  and  Management  of  Russian  Oil  Properties, 
including  Notes  on  the  Origin  of  Petroleum  in  Russia,  a  Descrip- 
tion of  the  Theory  and  Practice  of  Liquid  Fuel,  and  a  Translation 
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WEALE,  J.     A  Dictionary  of  Terms  Used  in  Architecture, 

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WEBB,  H.  L.     A  Practical  Guide  to  the  Testing  of  Insu- 
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WEEKES,  R.  W.  The  Design  of  Alternate  Current  Trans- 
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woodcut  illustrations.     8vo,  cloth $6 . 00 

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and  HERRMANN,  G.     Mechanics  of  Air  Machinery. 

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WEYMOUTH,  F.  M.     Drum  Armatures  and  Commutators. 

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64  D.  VAN  NOSTRAND  COMPANY'S 

WILLIAMSON,  R.  S.     On  the  Use  of  the  Barometer  on 

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WILLSON,    F.    N.      Theoretical    and    Practical    Graphics. 

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SCIENTIFIC   PUBLICATIONS.  65 

WOODBURY,  D.  V.     Treatise   on  the  Various  Elements 

of  Stability  in  the  Well-proportioned  Arch.  With  numerous 
tables  of  the  Ultimate  and  Actual  Thrust.  8vo,  half  morocco. 
Illustrated ., $4.00 

WRIGHT,  A.  C.    Analysis  of  Oils  and  Allied  Substances. 

Svo,  cloth,  illustrated,  241  pages net,  $3.50 

-  Simple  Method  for  Testing  Painters'  Materials.     8vo, 
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plications. Third  Edition,  revised  and  enlarged.  8vo,  cloth.  .$2.50 


-  and  HAYFORD,  J.  F.     Adjustment  of  Observations 

)  Geodetic 
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by  the  Method  of  Least  Squares,  with  applications  to  Geodetic 
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YOUNG,  J.  E.     Electrical  Testing  for  Telegraph  Engineers. 

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YOUNG   SEAMAN'S   MANUAL.     Compiled   from   Various 

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Marine  Schools.  8vo,  half  roan $3 . 00 

ZEUNER,  A.,  Dr.  Technical  Thermodynamics.  Trans- 
lated from  the  German,  by  Prof.  J.  F.  Klein,  Lehigh  University. 
8vo,  cloth,  illustrated In  Press. 

ZIMMER,  G.  F.  Mechanical  Handling  of  Material.  Be- 
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ZIPSER,  J.     Textile  Raw  Materials,  and  Their  Conversion 

into  Yarns.  The  study  of  the  Raw  Materials  and  the  Technology 
of  the  Spinning  Process.  A  Text-book  for  Textile,  Trade  and 
higher  Technical  Schools,  as  also  for  self- instruction.  Based  upon 
the  ordinary  syllabus  and  curriculum  of  the  Imperial  and  Royal 
Weaving  Schools.  Translated  from  the  German  by  Chas.  Salter. 
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Catalo^te  of  the  Van  Nostrand 
Science  Series. 


are  put  up  in  a  uniform,  neat,  and  attractive  form.     i8mo, 
boards.      Price  50  cents  per  volume.      The  subjects  are  of  an 
eminently  scientific  character  and  embrace  a  wide  range  of  topics,  and 
are  amply  illustrated  when  the  subject  demands. 

No.  i.  CHIMNEYS  FOR  FURNACES  AND  STEAM  BOILERS.  By 
R.  Armstrong,  C.E.  Third  American  Edition.  Revised  and 
partly  rewritten,  with  an  Appendix  on  "Theory  of  Chimney 
Draught,"  by  F.  E.  Idell,  M.E. 

No.  2.  STEAM-BOILER  EXPLOSIONS.  By  Zerah  Colburn.  New 
Edition,  revised  by  Prof.  R.  H.  Thurston. 

No.  3.  PRACTICAL  DESIGNING  OF  RETAINING-WALLS.  Fourth 
edition,  by  Prof.  W.  Cain. 

No.  4.  PROPORTIONS  OF  PINS  USED  IN  BRIDGES.  By  Charles 
E.  Bender,  C.E.  Second  edition,  with  Appendix. 

No.  5.  VENTILATION  OF  BUILDINGS.  By  Wm.  G.  Snow,  S.B.,  and 
Thos.  Nolan,  A.M. 

No.  6.  ON  THE  DESIGNING  AND   CONSTRUCTION  OF  STORAGE 

Reservoirs.     By  Arthur  Jacob,   B.A.     Third  American  edition, 
revised,  with  additions  by  E.  Sherman  Gould. 

No.  7.  SURCHARGED  AND  DIFFERENT  FORMS  OF  RETAINING- 

walls.     By  James  S.  Tate,  C.E. 

So.  8.  A  TREATISE  ON  THE  COMPOUND  STEAM-ENGINE.  By 
John  Turnbull,  Jr.  2nd  edition,  revised  by  Prof.  S.  W.  Robinson. 

No.  9.  A  TREATISE  ON  FUEL.  By  Arthur  V.  Abbott,  C.E.  Founded 
on  the  original  treatise  of  C.  William  Siemens,  D.C.L.  Third  ed. 

No.  10.  COMPOUND  ENGINES.     Translated  from  the  French  of  A. 

Mallet.     Second  edition,  revised  with  results  of  American  Prac- 
tice, by  Richard  H.  Buel,  C.E. 

No.  ii.  THEORY  OF  ARCHES.     By  Prof.  W.  Allan. 

No.  12.  THEORY  OF  VOUSSOIR  ARCHES.  By  Prof.  Wm.  Cain. 
Third  edition,  revised  and  enlarged. 

No.  13.  GASES  MET  WITH  IN  COAL  MINES.  By  J.  T.  Atkinson. 
Third  edition,  revised  and  enlarged,  to  which  is  added  The  Action 
of  Coal  Dusts  by  Edward  H.  Williams,  Jr. 


D.  VAN  NOSTRAND  CO.'S  SCIENTIFIC  PUBLICATIONS. 

No.  14.  FRICTION  OF  AIR  IN  MINES.  By  J.  J.  Atkinson.  Second 
American  edition. 

No.  15.  SKEW  ARCHES.  By  Prof.  E.  W.  Hyde,  C.E.  Illustrated. 
Second  edition. 

No.  16.  GRAPHIC  METHOD  FOR  SOLVING  CERTAIN  QUESTIONS 

in  Arithmetic  or  Algebra.  By  Prof.  G.  L.  Vose.  Second 
edition. 

No.  17.  WATER  AND  WATER-SUPPLY.  By  Prof.  W.  H.  Corfield, 
of  the  University  College,  London.  Second  American  edition. 

No.  18.  SEWERAGE   AND    SEWAGE   PURIFICATION.     By    M.    N. 

Baker,  Associate  Editor  "  Engineering  News."  Second  edition, 
revised  and  enlarged. 

No.  19.  STRENGTH  OF  BEAMS  UNDER  TRANSVERSE  LOADS. 
By  Prof.  W.  Allan,  author  of  "  Theory  of  Arches."  Second 
edition,  revised. 

No.  20.  BRIDGE  AND  TUNNEL  CENTRES.  By  John  B.  McMaster, 
C.E.  Second  edition. 

No.  21.  SAFETY  VALVES.     By  Richard  H.  Buel,  C.E.     Third  edition. 

No.  22.  HIGH  MASONRY  DAMS.  By  E.  Sherman  Gould,  M.  Am. 
Soc.  C.  E. 

No.  23.  THE  FATIGUE  OF  METALS  UNDER  REPEATED  STRAINS. 

With  various  Tables  of  Results  and  Experiments.  From  the 
German  of  Prof.  Ludwig  Spangenburg,  with  a  Preface  by  S.  H. 
Shreve,  A.M. 

No.  24.  A  PRACTICAL  TREATISE  ON  THE  TEETH  OF  WHEELS. 

By  Prof.  S.  W.  Robinson.     2nd  edition,  revised,  with  additions. 

No.  25.  THEORY  AND  CALCULATION  OF  CANTILEVER  BRIDGES. 
By  R.  M.  Wilcox. 

No.  26.  PRACTICAL  TREATISE  ON  THE  PROPERTIES  OF  CON- 

tinuous  Bridges.     By  Charles  Bender,  C.E. 

No.  27.  BOILER    INCRUSTATION    AND    CORROSION.     By    F.    J. 

Rowan.  New  edition.  Revised  and  partly  rewritten  by  F.  E. 
Idell. 

No.  28.  TRANSMISSION  OF  POWER  BY  WIRE  ROPES.     By  Albert 

W.  Stahl,  U.S.N.     Sesoni  edition,  revised. 

No.  29.  STEAM  INJECTORS,  THEIR  THEORY  AND  USE.  Trans- 
lated from  the  French  of  M.  Leon  Pochet. 

No.  30.  MAGNETISM    OF    IRON    VESSELS    AND    TERRESTRIAL 

Magnetism.     By  Prof.  Fairman  Rogers. 


D.  VAN  NOSTRAND  COMPANY'S 

No.  31.  THE    SANITARY   CONDITION   OF   CITY  AND   COUNTRY 

Dwelling-houses.     By  George  E.   Waring,  Jr.     Second   edition, 
revised. 

No.  32.  CABLE-MAKING    FOR    SUSPENSION    BRIDGES.    By    W. 

Hildenbrand,  C.E. 

No.  33.  MECHANICS  OF  VENTILATION.    By  George  W.  Rafter,  C.E. 

Second  edition,  revised. 

No.  34.  FOUNDATIONS.  By  Prof.  Jules  Gaudard,  C.E.  Trans- 
lated from  the  French.  Second  edition. 

No.  35-  THE  ANEROID  BAROMETER:  ITS  CONSTRUCTION  AND 
Use.  Compiled  by  George  W.  Plympton.  Ninth  edition, 
revised  and  enlarged. 

No.  36.  MATTER  AND  MOTION.  By  J.  Clerk  Maxwell,  M.A.  Second 
American  edition. 

No.  37.  GEOGRAPHICAL  SURVEYING:  ITS  USES,  METHODS, 
and  Results.  By  Frank  De  Yeaux  Carpenter,  C.E. 

No.  38.  MAXIMUM  STRESSES  IN  FRAMED  BRIDGES.  By  Prof. 
William  Cain,  A.M.,  C.E.  New  and  revised  edition. 

No.  39.  A    HANDBOOK    OF    THE    ELECTRO-MAGNETIC    TELE- 

graph.     By  A.  E.  Loring.     Fourth  edition,  revised. 

No.  40.  TRANSMISSION  OF  POWER  BY  COMPRESSED  AIR.     By 

Robert  Zahner,  M.E.     New  edition,  in  press. 

No.  41.  STRENGTH  OF  MATERIALS.  By  William  Kent,  C.E., 
Assoc.  Editor  "Engineering  News."  Second  edition. 

No.  42.  THEORY  OF  STEEL-CONCRETE  ARCHES,  AND  OF 

Vaulted    Structures.       By    Prof.    Wm.    Cain.      Third    edition, 
thoroughly  revised. 

No.  43.  WAVE  AND  VORTEX  MOTION.  By  Dr.  Thomas  Craig, 
of  Johns  Hopkins  University. 

No.  44.  TURBINE  WHEELS.  By  Prof.  W.  P.  Trowbridge,  Columbia 
College.  Second  edition.  Revised. 

No.  45.  THERMO-DYNAMICS.  By  Prof.  H.  T.  Eddy,  University 
of  Cincinnati.  New  edition,  in  press. 

No.  46.  ICE-MAKING  MACHINES.  From  the  French  of  M.  Le  Doux. 
Revised  by  Prof.  J.  E.  Denton,  D.  S.  Jacobus,  and  A.  Riesenberger. 
Fifth  edition,  revised. 

No.  47.  LINKAGES:  THE  DIFFERENT  FORMS  AND  USES  OF 
Articulated  Links.  By  J.  D.  C.  De  Roos. 

No.  48.  THEORY  OF  SOLID  AND  BRACED  ELASTIC  ARCHES 
By  William  Cain,  C.E. 

No.  49.  MOTION  OF  A  SOLID  IN  A  FLUID.     By  Thomas  Craig,  Ph.D. 


SCIENTIFIC  PUBLICATIONS. 

No.  50.  DWELLING-HOUSES:      THEIR     SANITARY     CONSTRUC- 

tion  and  Arrangements.     By  Prof.  W.  H.  Corfield. 

No.  51.  THE  TELESCOPE  :  OPTICAL  PRINCIPLES  INVOLVED  IN 
the  Construction  of  Refracting  and  Reflecting  Telescopes,  with 
a  new  chapter  on  the  Evolution  of  the  Modern  Telescope,  and  a 
Bibliography  to  date.  With  diagrams  and  folding  plates.  By 
Thomas  Nolan.  Second  edition,  revised  and  enlarged. 

No.  52.  IMAGINARY    QUANTITIES:     THEIR    GEOMETRICAL    IN- 

terpretation.     Translated  from    the    French    of    M.    Argand  by 
Prof.  A.  S.  Hardy. 

No.  53.  INDUCTION  COILS:  HOW  MADE  AND  HOW  USED. 
Eleventh  American  edition. 

No.  54.  KINEMATICS  OF  MACHINERY.  By  Prof.  Alex.  B.  W. 
Kennedy.  With  an  introduction  by  Prof.  R.  H.  Thurston. 

No.  55.  SEWER  GASES:  THEIR  NATURE  AND  ORIGIN.  By  A. 
de  Varona.  Second  edition,  revised  and  enlarged. 

No.  56.  THE  ACTUAL  LATERAL  PRESSURE  OF  EARTHWORK. 

By  Benj.  Baker,  M.  Inst.,  C.E. 

No.  57.  INCANDESCENT  ELECTRIC  LIGHTING.  A  Practical  De- 
scription of  the  Edison  System.  By  L.  H.  Latimer.  To 
which  is  added  the  Design  and  Operation  of  Incandescent  Sta- 
tions, by  C.  J.  Field ;  and  the  Maximum  Efficiency  of  Incandescent 
Lamps,  by  John  W.  How  ell. 

No.  58.  VENTILATION  OF  COAL  MINES.  By  W.  Fairley,  M.E., 
and  Geo.  J.  Andre. 

No.  59.  RAILROAD  ECONOMICS;    OR,  NOTES  WITH  COMMENTS. 

By  S.  W.  Robinson,  C.E. 

No.  60.  STRENGTH  OF  WROUGHT-IRON  BRIDGE  MEMBERS. 
By  S.  W.  Robinson,  C.E. 

No.  61.  POTABLE    WATER,    AND    METHODS    OF    DETECTING 

Impurities.     By  M.  N.  Baker.    Second  ed.,  revised  and  enlarged. 

No.  62.  THEORY  OF  THE  GAS-ENGINE.  By  Dougald  Clerk.  Third 
edition.  With  additional  matter.  Edited  by  F.  E.  Idell,  M.E. 

No.  63.  HOUSE-DRAINAGE  AND  SANITARY  PLUMBING.  By  W. 
P.  Gerhard.  Tenth  edition. 

No.  64.  ELECTRO-MAGNETS.     By  A.  N.  Mansfield. 

No.  65.  POCKET  LOGARITHMS  TO  FOUR  PLACES  OF  DECIMALS. 

Including  Logarithms  of  Numbers,  etc. 

No.  66.  DYNAMO-ELECTRIC  MACHINERY.  By  S.  P.  Thompson. 
With  an  Introduction  by  F.  L.  Pope.  Third  edition,  revised. 

No.  67.  HYDRAULIC  TABLES  FOR   THE  CALCULATION  OF    THE 

Discharge    through    Sewers,    Pipes,    and    Conduits.      Based    on 
"Kutter's  Formula."     By  P.  J.  Flynn. 


D.  VAN  NOSTRAND  COMPANY'S 

No.  68.  STEAM-HEATING.  By  Rebert  Briggs.  Third  edition,  re- 
vised, with  additions  by  A.  R.  Wolff. 

No.  69.  CHEMICAL  PROBLEMS.  By  Prof.  J.  C.  Foye.  Fourth 
edition,  revised  and  enlarged. 

No.  70.  EXPLOSIVE  MATERIALS.     By  Lieut  John  P.  Wisser. 

No.  71.  DYNAMIC  ELECTRICITY.  By  John  Hopkinson,  J.  A. 
Shoolbred,  and  R.  E.  Day. 

No.  72.  TOPOGRAPHICAL  SURVEYING.  By  George  J.  Specht 
Prof.  A.  S.  Hardy,  John  B.  McMaster,  and  H.  F.  Walling.  Third 
edition,  revised. 

No.  73.  SYMBOLIC  ALGEBRA;  OR,  THE  ALGEBRA  OF  ALGE- 

braic  Numbers.     By  Prof.  William  Cam. 

N».  74.  TESTING  MACHINES:  THEIR  HISTORY,  CONSTRUC- 
tion  and  Use.  By  Arthur  V.  Abbott. 

No.  75.  RECENT  PROGRESS  IN  DYNAMO-ELECTRIC  MACHINES. 

Being    a    Supplement    to    "Dynamo-electric    Machinery."      By 
Prof.  Sylvanus  P.  Thompson. 

No.  76.  MODERN  REPRODUCTIVE  GRAPHIC  PROCESSES.  By 
Lieut.  James  S.  Pettit,  U.S.A. 

No.  77.  STADIA  SURVEYING.  The  Theory  of  Stadia  Measure- 
ments. By  Arthur  Winslow.  Sixth  edition. 

No.  78.  THE  STEAM-ENGINE  INDICATOR  AND  ITS  USE.  By 
W.  B.  Le  Van. 

No.  79.  THE  FIGURE  OF  THE  EARTH.    By  Frank  C.  Roberts,  C.E. 

No.  80.  HEALTHY  FOUNDATIONS  FOR  HOUSES.  By  Glenn 
Brown. 

No.  81.  WATER  METERS:  COMPARATIVE  TESTS  OF  ACCURACY, 
Delivery,  etc.  Distinctive  features  of  the  Worthington,  Ken- 
nedy, Siemens,  and  Hesse  meters.  By  Ross  E.  Browne. 

No.  82.  THE  PRESERVATION  OF  TIMBER  BY  THE  USE  OF  ANTI- 
septics.  By  Samuel  Bagster  Boulton,  C.E. 

No.  83.  MECHANICAL  INTEGRATORS.  By  Prof.  Henry  S.  H. 
Shaw,  C.E. 

No.  84.  FLOW  OF  WATER  IN  OPEN  CHANNELS,  PIPES,  CON- 
duits,  Sewers,  etc.  With  Tables.  By  P.  J.  Flynn,  C.E. 

No.  85.  THE  LUMINIFEROUS  ./ETHER.     By  Prof.  De  Volson  Wood. 

No.  86.  HANDBOOK   OF   MINERALOGY:     DETERMINATION,    DE- 

scription,  and   Classification  of  Minerals   Found   in   the  United 
States.     By  Prof.  J.  C.  Foye.     Fifth  edition,  revised. 


SCIENTIFIC  PUBLICATIONS. 

No.  87.  TREATISE  ON  THE  THEORY  OF  THE  CONSTRUCTION 

of  Helicoidal  Oblique  Arches.     By  John  L.  Culley,  C.E. 

No.  88.  BEAMS  AND  GIRDERS.     Practical  Formulas  for  their  Resist- 
ance.    By  P.  H.  Philbrick. 

No.  89.  MODERN    GUN    COTTON:     ITS    MANUFACTURE,    PROP- 

erties,  and  Analyses.     By  Lieut.  John  P.  Wisser,  U  J3.A. 

No.  90.  ROTARY   MOTION  AS  APPLIED    TO    THE   GYROSCOPE. 

By  Major  J.  G.  Barnard. 

No.  91.  LEVELING:       BAROMETRIC,      TRIGONOMETRIC,      AND 

Spirit.     By  Prof.  I.  O.  Baker.    Second  edition. 

No.  92.  PETROLEUM:  ITS  PRODUCTION  AND  USE.  By  Boverton 
Redwood,  F.I.C.,  F.C.S. 

No.  93.  RECENT  PRACTICE  IN  THE  SANITARY  DRAINAGE  OF 

Buildings.  With  Memoranda  on  the  Cost  of  Plumbing  Work. 
Second  edition,  revised  and  enlarged.  By  William  Paul  Ger- 
hard, C.E. 

No.  94.  THE    TREATMENT    OF    SEWAGE.    By    Dr.    C.    Meymott 

Tidy. 

No.  95.  PLATE-GIRDER  CONSTRUCTION.  By  Isami  Hiroi,  C.E. 
Fourth  edition,  revised. 

No.  96.  ALTERNATE  CURRENT  MACHINERY.  By  Gisbert  Kapp, 
Assoc.  M.  Inst.,  C.E. 

No.  97-  THE  DISPOSAL  OF  HOUSEHOLD  WASTES.  By  W.  Paul 
Gerhard,  Sanitary  Engineer. 

No.  98.  PRACTICAL  DYNAMO-BUILDING  FOR  AMATEURS.  HOW 
to  Wind  for  Any  Output.  By  Frederick  Walker.  Fully  illus- 
trated. Third  edition. 


No.  99.  TRIPLE-EXPANSION    ENGINES    AND    ENGINE    TRIALS. 
By  P 
Well,  M.E. 


Prof.  Osborne  Reynolds.     Edited  with  notes,  etc.,  by  F.  E. 


No.  100.  HOW  TO  BECOME  AN  ENGINEER;    or,   The  Theoretical 

and  Practical  Training  necessary  in  Fitting  for  the  Duties  of 
the  Civil  Engineer.  By  Prof.  Geo.  W.  Plympton. 

No.  IGI.  THE  SEXTANT,  and  Other  Reflecting  Mathematical  Instru- 
ments. With  Practical  Hints  for  their  Adjustment  and  Use. 
By  F.  R.  Brainard,  U.  S.  Navy. 

No7io2.  THE     GALVANIC     CIRCUIT    INVESTIGATED     MATHE- 

matically  By  Dr.  G.  S.  Ohm,  Berlin,  1827.  Translated  fey 
William  Francis.  With  Preface  and  Notee  by  the  Editor,  Thomas 
D.  Lockwood,  M.I.E.E. 


D.  VAN  NOSTRAND  COMPANY'S 

No.  103.  THE  MICROSCOPICAL  EXAMINATION  OF  POTABLE 
Water.  With  Diagrams.  By  Geo.  W.  Rafter.  Second  edition. 

No.  104.  VAN  NOSTRAND'S  TABLE-BOOK  FOR  CIVIL  AND  ME- 

chanical  Engineers.     Compiled  by  Prof.  Geo.  W.  Plympton. 

No.  105.  DETERMINANTS.  An  Introduction  to  the  Study  of,  with 
Examples  and  Applications.  By  Prof.  G.  A.  Miller. 

No.  106.  COMPRESSED  AIR.  Experiments  upon  the  Transmission  of 
Power  by  Compressed  Air  in  Paris.  (Popp's  System.)  By 
Prof.  A.  B.  W.  Kennedy.  The  Transmission  and  Distribution 
of  Power  from  Central  Stations  by  Compressed  Air.  By  Prof. 
W.  C.  Unwin.  Edited  by  F.  E.  IdeU.  Third  edition. 

No.  107.  A  GRAPHICAL  METHOD  FOR  SWING  BRIDGES.  A 
Rational  and  Easy  Graphical  Analysis  of  the  Stresses  in  Ordinary 
Swing  Bridges.  With  an  Introduction  on  the  General  Theory 
of  Graphical  Statics,  with  Folding  Plates.  By  Benjamin  F. 
La  Rue. 

No.  108.  SLIDE-VALVE  DIAGRAMS.  A  French  Method  for  Con- 
structing Slide-valve  Diagrams.  By  Lloyd  Bankson,  B.S., 
Assistant  Naval  Constructor,  U.  S.  Navy.  8  Folding  Plates. 

No.  loo.  THE  MEASUREMENT  OF  ELECTRIC  CURRENTS.  Elec- 
trical Measuring  Instruments.  By  James  Swinburne.  Meters 
for  Electrical  Energy.  By  C.  H.  Wordingham.  Edited,  with 
Preface,  by  T.  Commerford  Martin.  With  Folding  Plate  and 
Numerous  Illustrations. 

No.  no.  TRANSITION  CURVES.  A  Field-book  for  Engineers,  Con- 
taining Rules  and  Tables  for  Laying  out  Transition  Curves.  By 
Walter  G.  Fox,  C.E. 

No.  in.  GAS-LIGHTING  AND  GAS-FITTING.  Specifications  and 
Rules  for  Gas-piping.  Notes  on  the  Advantages  of  Gas  for 
Cooking  and  Heating,  and  Useful  Hints  to  Gas  Consumers.  Third 
edition.  By  Wm.  Paul  Gerhard,  C.E. 

No.  112.  A  PRIMER  ON  THE  CALCULUS.  By  E.  Sherman  Gould, 
M.  Am.  Soc.  C.  E.  Third  edition,  revised  and  enlarged. 

No.  113.  PHYSICAL  PROBLEMS  and  Their  Solution.  By  A.  Bour- 
gougnon,  formerly  Assistant  at  Bellevue  Hospital.  Second  ed. 

No.  114.  MANUAL  OF  THE  SLIDE  RULE.  By  F.  A.  Halsey,  of 
the  "American  Machinist."  Third  edition,  corrected. 

No.  115.  TRAVERSE  TABLE.  Showing  the  Difference  of  Latitude 
and  Departure  for  Distances  Between  1  and  100  and  for  Angles  to 
Quarter  Degrees  Between  1  Degree  and  90  Degrees.  (Reprinted 
from  Seribner's  Pocket  Table  Book.) 


SCIENTIFIC  PUBLICATIONS. 

No.  116.  WORM  AND  SPIRAL  GEARING.  Reprinted  from  "  Ameri- 
can Machinist."  By  F.  A.  Halsey.  Second  revised  and  enlarged 
edition. 

No.  117.  PRACTICAL  HYDROSTATICS,  AND  HYDROSTATIC  FpR- 

mulas.      With    Numerous   Illustrative    Figures  and    Numerical 
Examples.     By  E.  Sherman  Gould 

No.  118.  TREATMENT  OF  SEPTIC  SEWAGE,  with  Diagrams  and 
Figures.  By  Geo.  W.  Rafter. 

No.  119.  LAY-OUT  OF  CORLISS  VALVE  GEARS.  With  Folding 
Plates  and  Diagrams.  By  Sanford  A.  Moss,  M.S  ,  Ph.D  Re- 
printed from  "The  American  Machinist,"  with  revisions  and 

additions.     Second  edition. 

No.  120.  ART  OF  GENERATING  GEAR  TEETH.  By  Howard  A. 
Coombs.  With  Figures,  Diagrams  and  Folding  Plates.  Re- 
printed from  the  "American  Machinist." 

No.  121.  ELEMENTS  OF  GAS  ENGINE  DESIGN.  Reprint  of  a  Set 
of  Notes  accompanying  a  Course  of  Lectures  delivered  at  Cornell 
University  in  1902.  By  Sanford  A.  Moss.  Illustrated. 

No.  122.  SHAFT  GOVERNORS.  By  W.  Trinks  and  C.  Housum.  Il- 
lustrated. 

No.  123.  FURNACE  DRAFT;  ITS  PRODUCTION  BY  MECHANICAL 
Methods.  A  Handy  Reference  Book,  with  figures  and  tables.  By 
William  Wallace  Christie.  Illustrated, 


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